summaryrefslogtreecommitdiff
path: root/kernel/module.c
AgeCommit message (Collapse)Author
2015-07-29module: weaken locking assertion for oops path.Rusty Russell
We don't actually hold the module_mutex when calling find_module_all from module_kallsyms_lookup_name: that's because it's used by the oops code and we don't want to deadlock. However, access to the list read-only is safe if preempt is disabled, so we can weaken the assertion. Keep a strong version for external callers though. Fixes: 0be964be0d45 ("module: Sanitize RCU usage and locking") Reported-by: He Kuang <hekuang@huawei.com> Cc: stable@kernel.org Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-07-09module: Fix load_module() error pathPeter Zijlstra
The load_module() error path frees a module but forgot to take it out of the mod_tree, leaving a dangling entry in the tree, causing havoc. Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reported-by: Arthur Marsh <arthur.marsh@internode.on.net> Tested-by: Arthur Marsh <arthur.marsh@internode.on.net> Fixes: 93c2e105f6bc ("module: Optimize __module_address() using a latched RB-tree") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-07-01Merge tag 'modules-next-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "Main excitement here is Peter Zijlstra's lockless rbtree optimization to speed module address lookup. He found some abusers of the module lock doing that too. A little bit of parameter work here too; including Dan Streetman's breaking up the big param mutex so writing a parameter can load another module (yeah, really). Unfortunately that broke the usual suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were appended too" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits) modules: only use mod->param_lock if CONFIG_MODULES param: fix module param locks when !CONFIG_SYSFS. rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE() module: add per-module param_lock module: make perm const params: suppress unused variable error, warn once just in case code changes. modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'. kernel/module.c: avoid ifdefs for sig_enforce declaration kernel/workqueue.c: remove ifdefs over wq_power_efficient kernel/params.c: export param_ops_bool_enable_only kernel/params.c: generalize bool_enable_only kernel/module.c: use generic module param operaters for sig_enforce kernel/params: constify struct kernel_param_ops uses sysfs: tightened sysfs permission checks module: Rework module_addr_{min,max} module: Use __module_address() for module_address_lookup() module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING module: Optimize __module_address() using a latched RB-tree rbtree: Implement generic latch_tree seqlock: Introduce raw_read_seqcount_latch() ...
2015-06-28param: fix module param locks when !CONFIG_SYSFS.Rusty Russell
As Dan Streetman points out, the entire point of locking for is to stop sysfs accesses, so they're elided entirely in the !SYSFS case. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-06-26Merge tag 'driver-core-4.2-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core updates from Greg KH: "Here is the driver core / firmware changes for 4.2-rc1. A number of small changes all over the place in the driver core, and in the firmware subsystem. Nothing really major, full details in the shortlog. Some of it is a bit of churn, given that the platform driver probing changes was found to not work well, so they were reverted. All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (31 commits) Revert "base/platform: Only insert MEM and IO resources" Revert "base/platform: Continue on insert_resource() error" Revert "of/platform: Use platform_device interface" Revert "base/platform: Remove code duplication" firmware: add missing kfree for work on async call fs: sysfs: don't pass count == 0 to bin file readers base:dd - Fix for typo in comment to function driver_deferred_probe_trigger(). base/platform: Remove code duplication of/platform: Use platform_device interface base/platform: Continue on insert_resource() error base/platform: Only insert MEM and IO resources firmware: use const for remaining firmware names firmware: fix possible use after free on name on asynchronous request firmware: check for file truncation on direct firmware loading firmware: fix __getname() missing failure check drivers: of/base: move of_init to driver_init drivers/base: cacheinfo: fix annoying typo when DT nodes are absent sysfs: disambiguate between "error code" and "failure" in comments driver-core: fix build for !CONFIG_MODULES driver-core: make __device_attach() static ...
2015-06-26Merge tag 'trace-v4.2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "This patch series contains several clean ups and even a new trace clock "monitonic raw". Also some enhancements to make the ring buffer even faster. But the biggest and most noticeable change is the renaming of the ftrace* files, structures and variables that have to deal with trace events. Over the years I've had several developers tell me about their confusion with what ftrace is compared to events. Technically, "ftrace" is the infrastructure to do the function hooks, which include tracing and also helps with live kernel patching. But the trace events are a separate entity altogether, and the files that affect the trace events should not be named "ftrace". These include: include/trace/ftrace.h -> include/trace/trace_events.h include/linux/ftrace_event.h -> include/linux/trace_events.h Also, functions that are specific for trace events have also been renamed: ftrace_print_*() -> trace_print_*() (un)register_ftrace_event() -> (un)register_trace_event() ftrace_event_name() -> trace_event_name() ftrace_trigger_soft_disabled() -> trace_trigger_soft_disabled() ftrace_define_fields_##call() -> trace_define_fields_##call() ftrace_get_offsets_##call() -> trace_get_offsets_##call() Structures have been renamed: ftrace_event_file -> trace_event_file ftrace_event_{call,class} -> trace_event_{call,class} ftrace_event_buffer -> trace_event_buffer ftrace_subsystem_dir -> trace_subsystem_dir ftrace_event_raw_##call -> trace_event_raw_##call ftrace_event_data_offset_##call-> trace_event_data_offset_##call ftrace_event_type_funcs_##call -> trace_event_type_funcs_##call And a few various variables and flags have also been updated. This has been sitting in linux-next for some time, and I have not heard a single complaint about this rename breaking anything. Mostly because these functions, variables and structures are mostly internal to the tracing system and are seldom (if ever) used by anything external to that" * tag 'trace-v4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) ring_buffer: Allow to exit the ring buffer benchmark immediately ring-buffer-benchmark: Fix the wrong type ring-buffer-benchmark: Fix the wrong param in module_param ring-buffer: Add enum names for the context levels ring-buffer: Remove useless unused tracing_off_permanent() ring-buffer: Give NMIs a chance to lock the reader_lock ring-buffer: Add trace_recursive checks to ring_buffer_write() ring-buffer: Allways do the trace_recursive checks ring-buffer: Move recursive check to per_cpu descriptor ring-buffer: Add unlikelys to make fast path the default tracing: Rename ftrace_get_offsets_##call() to trace_event_get_offsets_##call() tracing: Rename ftrace_define_fields_##call() to trace_event_define_fields_##call() tracing: Rename ftrace_event_type_funcs_##call to trace_event_type_funcs_##call tracing: Rename ftrace_data_offset_##call to trace_event_data_offset_##call tracing: Rename ftrace_raw_##call event structures to trace_event_raw_##call tracing: Rename ftrace_trigger_soft_disabled() to trace_trigger_soft_disabled() tracing: Rename FTRACE_EVENT_FL_* flags to EVENT_FILE_FL_* tracing: Rename struct ftrace_subsystem_dir to trace_subsystem_dir tracing: Rename ftrace_event_name() to trace_event_name() tracing: Rename FTRACE_MAX_EVENT to TRACE_EVENT_TYPE_MAX ...
2015-06-23module: add per-module param_lockDan Streetman
Add a "param_lock" mutex to each module, and update params.c to use the correct built-in or module mutex while locking kernel params. Remove the kparam_block_sysfs_r/w() macros, replace them with direct calls to kernel_param_[un]lock(module). The kernel param code currently uses a single mutex to protect modification of any and all kernel params. While this generally works, there is one specific problem with it; a module callback function cannot safely load another module, i.e. with request_module() or even with indirect calls such as crypto_has_alg(). If the module to be loaded has any of its params configured (e.g. with a /etc/modprobe.d/* config file), then the attempt will result in a deadlock between the first module param callback waiting for modprobe, and modprobe trying to lock the single kernel param mutex to set the new module's param. This fixes that by using per-module mutexes, so that each individual module is protected against concurrent changes in its own kernel params, but is not blocked by changes to other module params. All built-in modules continue to use the built-in mutex, since they will always be loaded at runtime and references (e.g. request_module(), crypto_has_alg()) to them will never cause load-time param changing. This also simplifies the interface used by modules to block sysfs access to their params; while there are currently functions to block and unblock sysfs param access which are split up by read and write and expect a single kernel param to be passed, their actual operation is identical and applies to all params, not just the one passed to them; they simply lock and unlock the global param mutex. They are replaced with direct calls to kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or if the module is built-in, it locks the built-in mutex. Suggested-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-06-08Merge 4.1-rc7 into driver-core-nextGreg Kroah-Hartman
We want the fixes in this branch as well for testing and merge resolution. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-28kernel/module.c: avoid ifdefs for sig_enforce declarationLuis R. Rodriguez
There's no need to require an ifdef over the declaration of sig_enforce as IS_ENABLED() can be used. While at it, there's no harm in exposing this kernel parameter outside of CONFIG_MODULE_SIG as it'd be a no-op on non module sig kernels. Now, technically we should in theory be able to remove the #ifdef'ery over the declaration of the module parameter as we are also trusting the bool_enable_only code for CONFIG_MODULE_SIG kernels but for now remain paranoid and keep it. With time if no one can put a bullet through bool_enable_only and if there are no technical requirements over not exposing CONFIG_MODULE_SIG_FORCE with the measures in place by bool_enable_only we could remove this last ifdef. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kees Cook <keescook@chromium.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: cocci@systeme.lip6.fr Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28kernel/params.c: generalize bool_enable_onlyLuis R. Rodriguez
This takes out the bool_enable_only implementation from the module loading code and generalizes it so that others can make use of it. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kees Cook <keescook@chromium.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: cocci@systeme.lip6.fr Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28kernel/module.c: use generic module param operaters for sig_enforceLuis R. Rodriguez
We're directly checking and modifying sig_enforce when needed instead of using the generic helpers. This prevents us from generalizing this helper so that others can use it. Use indirect helpers to allow us to generalize this code a bit and to make it a bit more clear what this is doing. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kees Cook <keescook@chromium.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: cocci@systeme.lip6.fr Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28module: Rework module_addr_{min,max}Peter Zijlstra
__module_address() does an initial bound check before doing the {list/tree} iteration to find the actual module. The bound variables are nowhere near the mod_tree cacheline, in fact they're nowhere near one another. module_addr_min lives in .data while module_addr_max lives in .bss (smarty pants GCC thinks the explicit 0 assignment is a mistake). Rectify this by moving the two variables into a structure together with the latch_tree_root to guarantee they all share the same cacheline and avoid hitting two extra cachelines for the lookup. While reworking the bounds code, move the bound update from allocation to insertion time, this avoids updating the bounds for a few error paths. Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28module: Use __module_address() for module_address_lookup()Peter Zijlstra
Use the generic __module_address() addr to struct module lookup instead of open coding it once more. Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACINGPeter Zijlstra
Andrew worried about the overhead on small systems; only use the fancy code when either perf or tracing is enabled. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Requested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28module: Optimize __module_address() using a latched RB-treePeter Zijlstra
Currently __module_address() is using a linear search through all modules in order to find the module corresponding to the provided address. With a lot of modules this can take a lot of time. One of the users of this is kernel_text_address() which is employed in many stack unwinders; which in turn are used by perf-callchain and ftrace (possibly from NMI context). So by optimizing __module_address() we optimize many stack unwinders which are used by both perf and tracing in performance sensitive code. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-28module: Sanitize RCU usage and lockingPeter Zijlstra
Currently the RCU usage in module is an inconsistent mess of RCU and RCU-sched, this is broken for CONFIG_PREEMPT where synchronize_rcu() does not imply synchronize_sched(). Most usage sites use preempt_{dis,en}able() which is RCU-sched, but (most of) the modification sites use synchronize_rcu(). With the exception of the module bug list, which actually uses RCU. Convert everything over to RCU-sched. Furthermore add lockdep asserts to all sites, because it's not at all clear to me the required locking is observed, esp. on exported functions. Cc: Rusty Russell <rusty@rustcorp.com.au> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-27module: Annotate module version magicPeter Zijlstra
Due to the new lockdep checks in the coming patch, we go: [ 9.759380] ------------[ cut here ]------------ [ 9.759389] WARNING: CPU: 31 PID: 597 at ../kernel/module.c:216 each_symbol_section+0x121/0x130() [ 9.759391] Modules linked in: [ 9.759393] CPU: 31 PID: 597 Comm: modprobe Not tainted 4.0.0-rc1+ #65 [ 9.759393] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013 [ 9.759396] ffffffff817d8676 ffff880424567ca8 ffffffff8157e98b 0000000000000001 [ 9.759398] 0000000000000000 ffff880424567ce8 ffffffff8105fbc7 ffff880424567cd8 [ 9.759400] 0000000000000000 ffffffff810ec160 ffff880424567d40 0000000000000000 [ 9.759400] Call Trace: [ 9.759407] [<ffffffff8157e98b>] dump_stack+0x4f/0x7b [ 9.759410] [<ffffffff8105fbc7>] warn_slowpath_common+0x97/0xe0 [ 9.759412] [<ffffffff810ec160>] ? section_objs+0x60/0x60 [ 9.759414] [<ffffffff8105fc2a>] warn_slowpath_null+0x1a/0x20 [ 9.759415] [<ffffffff810ed9c1>] each_symbol_section+0x121/0x130 [ 9.759417] [<ffffffff810eda01>] find_symbol+0x31/0x70 [ 9.759420] [<ffffffff810ef5bf>] load_module+0x20f/0x2660 [ 9.759422] [<ffffffff8104ef10>] ? __do_page_fault+0x190/0x4e0 [ 9.759426] [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13 [ 9.759427] [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13 [ 9.759433] [<ffffffff810ae73d>] ? trace_hardirqs_on_caller+0x11d/0x1e0 [ 9.759437] [<ffffffff812fcc0e>] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 9.759439] [<ffffffff815880ec>] ? retint_restore_args+0x13/0x13 [ 9.759441] [<ffffffff810f1ade>] SyS_init_module+0xce/0x100 [ 9.759443] [<ffffffff81587429>] system_call_fastpath+0x12/0x17 [ 9.759445] ---[ end trace 9294429076a9c644 ]--- As per the comment this site should be fine, but lets wrap it in preempt_disable() anyhow to placate lockdep. Cc: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-05-20driver-core: add driver module asynchronous probe supportLuis R. Rodriguez
Some init systems may wish to express the desire to have device drivers run their probe() code asynchronously. This implements support for this and allows userspace to request async probe as a preference through a generic shared device driver module parameter, async_probe. Implementation for async probe is supported through a module parameter given that since synchronous probe has been prevalent for years some userspace might exist which relies on the fact that the device driver will probe synchronously and the assumption that devices it provides will be immediately available after this. Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-20module: add extra argument for parse_params() callbackLuis R. Rodriguez
This adds an extra argument onto parse_params() to be used as a way to make the unused callback a bit more useful and generic by allowing the caller to pass on a data structure of its choice. An example use case is to allow us to easily make module parameters for every module which we will do next. @ parse @ identifier name, args, params, num, level_min, level_max; identifier unknown, param, val, doing; type s16; @@ extern char *parse_args(const char *name, char *args, const struct kernel_param *params, unsigned num, s16 level_min, s16 level_max, + void *arg, int (*unknown)(char *param, char *val, const char *doing + , void *arg )); @ parse_mod @ identifier name, args, params, num, level_min, level_max; identifier unknown, param, val, doing; type s16; @@ char *parse_args(const char *name, char *args, const struct kernel_param *params, unsigned num, s16 level_min, s16 level_max, + void *arg, int (*unknown)(char *param, char *val, const char *doing + , void *arg )) { ... } @ parse_args_found @ expression R, E1, E2, E3, E4, E5, E6; identifier func; @@ ( R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, func); | R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, &func); | R = parse_args(E1, E2, E3, E4, E5, E6, + NULL, NULL); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, func); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, &func); | parse_args(E1, E2, E3, E4, E5, E6, + NULL, NULL); ) @ parse_args_unused depends on parse_args_found @ identifier parse_args_found.func; @@ int func(char *param, char *val, const char *unused + , void *arg ) { ... } @ mod_unused depends on parse_args_found @ identifier parse_args_found.func; expression A1, A2, A3; @@ - func(A1, A2, A3); + func(A1, A2, A3, NULL); Generated-by: Coccinelle SmPL Cc: cocci@systeme.lip6.fr Cc: Tejun Heo <tj@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Christoph Hellwig <hch@infradead.org> Cc: Felipe Contreras <felipe.contreras@gmail.com> Cc: Ewan Milne <emilne@redhat.com> Cc: Jean Delvare <jdelvare@suse.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Jani Nikula <jani.nikula@intel.com> Cc: linux-kernel@vger.kernel.org Reviewed-by: Tejun Heo <tj@kernel.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-05-13tracing: Rename ftrace_event.h to trace_events.hSteven Rostedt (Red Hat)
The term "ftrace" is really the infrastructure of the function hooks, and not the trace events. Rename ftrace_event.h to trace_events.h to represent the trace_event infrastructure and decouple the term ftrace from it. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-05-09module: Call module notifier on failure after complete_formation()Steven Rostedt
The module notifier call chain for MODULE_STATE_COMING was moved up before the parsing of args, into the complete_formation() call. But if the module failed to load after that, the notifier call chain for MODULE_STATE_GOING was never called and that prevented the users of those call chains from cleaning up anything that was allocated. Link: http://lkml.kernel.org/r/554C52B9.9060700@gmail.com Reported-by: Pontus Fuchs <pontus.fuchs@gmail.com> Fixes: 4982223e51e8 "module: set nx before marking module MODULE_STATE_COMING" Cc: stable@vger.kernel.org # 3.16+ Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-04-22Merge tag 'modules-next-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "Quentin opened a can of worms by adding extable entry checking to modpost, but most architectures seem fixed now. Thanks to all involved. Last minute rebase because I noticed a "[PATCH]" had snuck into a commit message somehow" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: modpost: don't emit section mismatch warnings for compiler optimizations modpost: expand pattern matching to support substring matches modpost: do not try to match the SHT_NUL section. modpost: fix extable entry size calculation. modpost: fix inverted logic in is_extable_fault_address(). modpost: handle -ffunction-sections modpost: Whitelist .text.fixup and .exception.text params: handle quotes properly for values not of form foo="bar". modpost: document the use of struct section_check. modpost: handle relocations mismatch in __ex_table. scripts: add check_extable.sh script. modpost: mismatch_handler: retrieve tosym information only when needed. modpost: factorize symbol pretty print in get_pretty_name(). modpost: add handler function pointer to sectioncheck. modpost: add .sched.text and .kprobes.text to the TEXT_SECTIONS list. modpost: add strict white-listing when referencing sections. module: do not print allocation-fail warning on bogus user buffer size kernel/module.c: fix typos in message about unused symbols
2015-04-14Merge tag 'trace-v4.1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: "Some clean ups and small fixes, but the biggest change is the addition of the TRACE_DEFINE_ENUM() macro that can be used by tracepoints. Tracepoints have helper functions for the TP_printk() called __print_symbolic() and __print_flags() that lets a numeric number be displayed as a a human comprehensible text. What is placed in the TP_printk() is also shown in the tracepoint format file such that user space tools like perf and trace-cmd can parse the binary data and express the values too. Unfortunately, the way the TRACE_EVENT() macro works, anything placed in the TP_printk() will be shown pretty much exactly as is. The problem arises when enums are used. That's because unlike macros, enums will not be changed into their values by the C pre-processor. Thus, the enum string is exported to the format file, and this makes it useless for user space tools. The TRACE_DEFINE_ENUM() solves this by converting the enum strings in the TP_printk() format into their number, and that is what is shown to user space. For example, the tracepoint tlb_flush currently has this in its format file: __print_symbolic(REC->reason, { TLB_FLUSH_ON_TASK_SWITCH, "flush on task switch" }, { TLB_REMOTE_SHOOTDOWN, "remote shootdown" }, { TLB_LOCAL_SHOOTDOWN, "local shootdown" }, { TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" }) After adding: TRACE_DEFINE_ENUM(TLB_FLUSH_ON_TASK_SWITCH); TRACE_DEFINE_ENUM(TLB_REMOTE_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_SHOOTDOWN); TRACE_DEFINE_ENUM(TLB_LOCAL_MM_SHOOTDOWN); Its format file will contain this: __print_symbolic(REC->reason, { 0, "flush on task switch" }, { 1, "remote shootdown" }, { 2, "local shootdown" }, { 3, "local mm shootdown" })" * tag 'trace-v4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (27 commits) tracing: Add enum_map file to show enums that have been mapped writeback: Export enums used by tracepoint to user space v4l: Export enums used by tracepoints to user space SUNRPC: Export enums in tracepoints to user space mm: tracing: Export enums in tracepoints to user space irq/tracing: Export enums in tracepoints to user space f2fs: Export the enums in the tracepoints to userspace net/9p/tracing: Export enums in tracepoints to userspace x86/tlb/trace: Export enums in used by tlb_flush tracepoint tracing/samples: Update the trace-event-sample.h with TRACE_DEFINE_ENUM() tracing: Allow for modules to convert their enums to values tracing: Add TRACE_DEFINE_ENUM() macro to map enums to their values tracing: Update trace-event-sample with TRACE_SYSTEM_VAR documentation tracing: Give system name a pointer brcmsmac: Move each system tracepoints to their own header iwlwifi: Move each system tracepoints to their own header mac80211: Move message tracepoints to their own header tracing: Add TRACE_SYSTEM_VAR to xhci-hcd tracing: Add TRACE_SYSTEM_VAR to kvm-s390 tracing: Add TRACE_SYSTEM_VAR to intel-sst ...
2015-04-08Copy the kernel module data from user space in chunksLinus Torvalds
Unlike most (all?) other copies from user space, kernel module loading is almost unlimited in size. So we do a potentially huge "copy_from_user()" when we copy the module data from user space to the kernel buffer, which can be a latency concern when preemption is disabled (or voluntary). Also, because 'copy_from_user()' clears the tail of the kernel buffer on failures, even a *failed* copy can end up wasting a lot of time. Normally neither of these are concerns in real life, but they do trigger when doing stress-testing with trinity. Running in a VM seems to add its own overheadm causing trinity module load testing to even trigger the watchdog. The simple fix is to just chunk up the module loading, so that it never tries to copy insanely big areas in one go. That bounds the latency, and also the amount of (unnecessarily, in this case) cleared memory for the failure case. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-08tracing: Allow for modules to convert their enums to valuesSteven Rostedt (Red Hat)
Update the infrastructure such that modules that declare TRACE_DEFINE_ENUM() will have those enums converted into their values in the tracepoint print fmt strings. Link: http://lkml.kernel.org/r/87vbhjp74q.fsf@rustcorp.com.au Acked-by: Rusty Russell <rusty@rustcorp.com.au> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-03-24module: do not print allocation-fail warning on bogus user buffer sizeKirill A. Shutemov
init_module(2) passes user-specified buffer length directly to vmalloc(). It makes warn_alloc_failed() to print out a lot of info into dmesg if user specified insane size, like -1. Let's silence the warning. It doesn't add much value to -ENOMEM return code. Without the patch the syscall is prohibitive noisy for testing with trinity. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Jones <davej@codemonkey.org.uk> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-03-24kernel/module.c: fix typos in message about unused symbolsYannick Guerrini
Fix typos in pr_warn message about unused symbols Signed-off-by: Yannick Guerrini <yguerrini@tomshardware.fr> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-03-23lockdep: Fix the module unload key range freeing logicPeter Zijlstra
Module unload calls lockdep_free_key_range(), which removes entries from the data structures. Most of the lockdep code OTOH assumes the data structures are append only; in specific see the comments in add_lock_to_list() and look_up_lock_class(). Clearly this has only worked by accident; make it work proper. The actual scenario to make it go boom would involve the memory freed by the module unlock being re-allocated and re-used for a lock inside of a rcu-sched grace period. This is a very unlikely scenario, still better plug the hole. Use RCU list iteration in all places and ammend the comments. Change lockdep_free_key_range() to issue a sync_sched() between removal from the lists and returning -- which results in the memory being freed. Further ensure the callers are placed correctly and comment the requirements. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Tsyvarev <tsyvarev@ispras.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-03-12kasan, module, vmalloc: rework shadow allocation for modulesAndrey Ryabinin
Current approach in handling shadow memory for modules is broken. Shadow memory could be freed only after memory shadow corresponds it is no longer used. vfree() called from interrupt context could use memory its freeing to store 'struct llist_node' in it: void vfree(const void *addr) { ... if (unlikely(in_interrupt())) { struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred); if (llist_add((struct llist_node *)addr, &p->list)) schedule_work(&p->wq); Later this list node used in free_work() which actually frees memory. Currently module_memfree() called in interrupt context will free shadow before freeing module's memory which could provoke kernel crash. So shadow memory should be freed after module's memory. However, such deallocation order could race with kasan_module_alloc() in module_alloc(). Free shadow right before releasing vm area. At this point vfree()'d memory is not used anymore and yet not available for other allocations. New VM_KASAN flag used to indicate that vm area has dynamically allocated shadow memory so kasan frees shadow only if it was previously allocated. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-03-06kernel/module.c: Update debug alignment after symtable generationLaura Abbott
When CONFIG_DEBUG_SET_MODULE_RONX is enabled, the sizes of module sections are aligned up so appropriate permissions can be applied. Adjusting for the symbol table may cause them to become unaligned. Make sure to re-align the sizes afterward. Signed-off-by: Laura Abbott <lauraa@codeaurora.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2015-02-17kernel/module.c: do not inline do_init_module()Jan Kiszka
This provides a reliable breakpoint target, required for automatic symbol loading via the gdb helper command 'lx-symbols'. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ben Widawsky <ben@bwidawsk.net> Cc: Borislav Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13kasan: enable instrumentation of global variablesAndrey Ryabinin
This feature let us to detect accesses out of bounds of global variables. This will work as for globals in kernel image, so for globals in modules. Currently this won't work for symbols in user-specified sections (e.g. __init, __read_mostly, ...) The idea of this is simple. Compiler increases each global variable by redzone size and add constructors invoking __asan_register_globals() function. Information about global variable (address, size, size with redzone ...) passed to __asan_register_globals() so we could poison variable's redzone. This patch also forces module_alloc() to return 8*PAGE_SIZE aligned address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) more simple. Such alignment guarantees that each shadow page backing modules address space correspond to only one module_alloc() allocation. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11module: Replace over-engineered nested sleepPeter Zijlstra
Since the introduction of the nested sleep warning; we've established that the occasional sleep inside a wait_event() is fine. wait_event() loops are invariant wrt. spurious wakeups, and the occasional sleep has a similar effect on them. As long as its occasional its harmless. Therefore replace the 'correct' but verbose wait_woken() thing with a simple annotation to shut up the warning. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-02-11module: Annotate nested sleep in resolve_symbol()Peter Zijlstra
Because wait_event() loops are safe vs spurious wakeups we can allow the occasional sleep -- which ends up being very similar. Reported-by: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-02-06module: Remove double spaces in module verification taint messageMarcel Holtmann
The warning message when loading modules with a wrong signature has two spaces in it: "module verification failed: signature and/or required key missing" Signed-off-by: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-02-06kernel/module.c: Free lock-classes if parse_args failedAndrey Tsyvarev
parse_args call module parameters' .set handlers, which may use locks defined in the module. So, these classes should be freed in case parse_args returns error(e.g. due to incorrect parameter passed). Signed-off-by: Andrey Tsyvarev <tsyvarev@ispras.ru> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-01-22module: make module_refcount() a signed integer.Rusty Russell
James Bottomley points out that it will be -1 during unload. It's only used for diagnostics, so let's not hide that as it could be a clue as to what's gone wrong. Cc: Jason Wessel <jason.wessel@windriver.com> Acked-and-documention-added-by: James Bottomley <James.Bottomley@HansenPartnership.com> Reviewed-by: Masami Hiramatsu <maasami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-01-20module: fix race in kallsyms resolution during module load success.Rusty Russell
The kallsyms routines (module_symbol_name, lookup_module_* etc) disable preemption to walk the modules rather than taking the module_mutex: this is because they are used for symbol resolution during oopses. This works because there are synchronize_sched() and synchronize_rcu() in the unload and failure paths. However, there's one case which doesn't have that: the normal case where module loading succeeds, and we free the init section. We don't want a synchronize_rcu() there, because it would slow down module loading: this bug was introduced in 2009 to speed module loading in the first place. Thus, we want to do the free in an RCU callback. We do this in the simplest possible way by allocating a new rcu_head: if we put it in the module structure we'd have to worry about that getting freed. Reported-by: Rui Xiang <rui.xiang@huawei.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2015-01-20module: remove mod arg from module_free, rename module_memfree().Rusty Russell
Nothing needs the module pointer any more, and the next patch will call it from RCU, where the module itself might no longer exist. Removing the arg is the safest approach. This just codifies the use of the module_alloc/module_free pattern which ftrace and bpf use. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Ley Foon Tan <lftan@altera.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: x86@kernel.org Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: linux-cris-kernel@axis.com Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: nios2-dev@lists.rocketboards.org Cc: linuxppc-dev@lists.ozlabs.org Cc: sparclinux@vger.kernel.org Cc: netdev@vger.kernel.org
2015-01-20module_arch_freeing_init(): new hook for archs before module->module_init freed.Rusty Russell
Archs have been abusing module_free() to clean up their arch-specific allocations. Since module_free() is also (ab)used by BPF and trace code, let's keep it to simple allocations, and provide a hook called before that. This means that avr32, ia64, parisc and s390 no longer need to implement their own module_free() at all. avr32 doesn't need module_finalize() either. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: linux-kernel@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-parisc@vger.kernel.org Cc: linux-s390@vger.kernel.org
2014-12-18Merge tag 'modules-next-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module updates from Rusty Russell: "The exciting thing here is the getting rid of stop_machine on module removal. This is possible by using a simple atomic_t for the counter, rather than our fancy per-cpu counter: it turns out that no one is doing a module increment per net packet, so the slowdown should be in the noise" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: param: do not set store func without write perm params: cleanup sysfs allocation kernel:module Fix coding style errors and warnings. module: Remove stop_machine from module unloading module: Replace module_ref with atomic_t refcnt lib/bug: Use RCU list ops for module_bug_list module: Unlink module with RCU synchronizing instead of stop_machine module: Wait for RCU synchronizing before releasing a module
2014-11-11kernel:module Fix coding style errors and warnings.Ionut Alexa
Fixed codin style errors and warnings. Changes printk with print_debug/warn. Changed seq_printf to seq_puts. Signed-off-by: Ionut Alexa <ionut.m.alexa@gmail.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed bogus KERN_DEFAULT conversion)
2014-11-11module: Remove stop_machine from module unloadingMasami Hiramatsu
Remove stop_machine from module unloading by adding new reference counting algorithm. This atomic refcounter works like a semaphore, it can get (be incremented) only when the counter is not 0. When loading a module, kmodule subsystem sets the counter MODULE_REF_BASE (= 1). And when unloading the module, it subtracts MODULE_REF_BASE from the counter. If no one refers the module, the refcounter becomes 0 and we can remove the module safely. If someone referes it, we try to recover the counter by adding MODULE_REF_BASE unless the counter becomes 0, because the referrer can put the module right before recovering. If the recovering is failed, we can get the 0 refcount and it never be incremented again, it can be removed safely too. Note that __module_get() forcibly gets the module refcounter, users should use try_module_get() instead of that. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-11-11module: Replace module_ref with atomic_t refcntMasami Hiramatsu
Replace module_ref per-cpu complex reference counter with an atomic_t simple refcnt. This is for code simplification. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-11-11lib/bug: Use RCU list ops for module_bug_listMasami Hiramatsu
Actually since module_bug_list should be used in BUG context, we may not need this. But for someone who want to use this from normal context, this makes module_bug_list an RCU list. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-11-11module: Unlink module with RCU synchronizing instead of stop_machineMasami Hiramatsu
Unlink module from module list with RCU synchronizing instead of using stop_machine(). Since module list is already protected by rcu, we don't need stop_machine() anymore. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-11-11module: Wait for RCU synchronizing before releasing a moduleMasami Hiramatsu
Wait for RCU synchronizing on failure path of module loading before releasing struct module, because the memory of mod->list can still be accessed by list walkers (e.g. kallsyms). Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-10-28sched, modules: Fix nested sleep in add_unformed_module()Peter Zijlstra
This is a genuine bug in add_unformed_module(), we cannot use blocking primitives inside a wait loop. So rewrite the wait_event_interruptible() usage to use the fresh wait_woken() stuff. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: oleg@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: http://lkml.kernel.org/r/20140924082242.458562904@infradead.org [ So this is probably complex to backport and the race wasn't reported AFAIK, so not marked for -stable. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-10-18Merge tag 'modules-next-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module fix from Rusty Russell: "A single panic fix for a rare race, stable CC'd" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: modules, lock around setting of MODULE_STATE_UNFORMED
2014-10-15modules, lock around setting of MODULE_STATE_UNFORMEDPrarit Bhargava
A panic was seen in the following sitation. There are two threads running on the system. The first thread is a system monitoring thread that is reading /proc/modules. The second thread is loading and unloading a module (in this example I'm using my simple dummy-module.ko). Note, in the "real world" this occurred with the qlogic driver module. When doing this, the following panic occurred: ------------[ cut here ]------------ kernel BUG at kernel/module.c:3739! invalid opcode: 0000 [#1] SMP Modules linked in: binfmt_misc sg nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache intel_powerclamp coretemp kvm_intel kvm crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel lrw igb gf128mul glue_helper iTCO_wdt iTCO_vendor_support ablk_helper ptp sb_edac cryptd pps_core edac_core shpchp i2c_i801 pcspkr wmi lpc_ich ioatdma mfd_core dca ipmi_si nfsd ipmi_msghandler auth_rpcgss nfs_acl lockd sunrpc xfs libcrc32c sr_mod cdrom sd_mod crc_t10dif crct10dif_common mgag200 syscopyarea sysfillrect sysimgblt i2c_algo_bit drm_kms_helper ttm isci drm libsas ahci libahci scsi_transport_sas libata i2c_core dm_mirror dm_region_hash dm_log dm_mod [last unloaded: dummy_module] CPU: 37 PID: 186343 Comm: cat Tainted: GF O-------------- 3.10.0+ #7 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 task: ffff8807fd2d8000 ti: ffff88080fa7c000 task.ti: ffff88080fa7c000 RIP: 0010:[<ffffffff810d64c5>] [<ffffffff810d64c5>] module_flags+0xb5/0xc0 RSP: 0018:ffff88080fa7fe18 EFLAGS: 00010246 RAX: 0000000000000003 RBX: ffffffffa03b5200 RCX: 0000000000000000 RDX: 0000000000001000 RSI: ffff88080fa7fe38 RDI: ffffffffa03b5000 RBP: ffff88080fa7fe28 R08: 0000000000000010 R09: 0000000000000000 R10: 0000000000000000 R11: 000000000000000f R12: ffffffffa03b5000 R13: ffffffffa03b5008 R14: ffffffffa03b5200 R15: ffffffffa03b5000 FS: 00007f6ae57ef740(0000) GS:ffff88101e7a0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000404f70 CR3: 0000000ffed48000 CR4: 00000000001407e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffffffffa03b5200 ffff8810101e4800 ffff88080fa7fe70 ffffffff810d666c ffff88081e807300 000000002e0f2fbf 0000000000000000 ffff88100f257b00 ffffffffa03b5008 ffff88080fa7ff48 ffff8810101e4800 ffff88080fa7fee0 Call Trace: [<ffffffff810d666c>] m_show+0x19c/0x1e0 [<ffffffff811e4d7e>] seq_read+0x16e/0x3b0 [<ffffffff812281ed>] proc_reg_read+0x3d/0x80 [<ffffffff811c0f2c>] vfs_read+0x9c/0x170 [<ffffffff811c1a58>] SyS_read+0x58/0xb0 [<ffffffff81605829>] system_call_fastpath+0x16/0x1b Code: 48 63 c2 83 c2 01 c6 04 03 29 48 63 d2 eb d9 0f 1f 80 00 00 00 00 48 63 d2 c6 04 13 2d 41 8b 0c 24 8d 50 02 83 f9 01 75 b2 eb cb <0f> 0b 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 RIP [<ffffffff810d64c5>] module_flags+0xb5/0xc0 RSP <ffff88080fa7fe18> Consider the two processes running on the system. CPU 0 (/proc/modules reader) CPU 1 (loading/unloading module) CPU 0 opens /proc/modules, and starts displaying data for each module by traversing the modules list via fs/seq_file.c:seq_open() and fs/seq_file.c:seq_read(). For each module in the modules list, seq_read does op->start() <-- this is a pointer to m_start() op->show() <- this is a pointer to m_show() op->stop() <-- this is a pointer to m_stop() The m_start(), m_show(), and m_stop() module functions are defined in kernel/module.c. The m_start() and m_stop() functions acquire and release the module_mutex respectively. ie) When reading /proc/modules, the module_mutex is acquired and released for each module. m_show() is called with the module_mutex held. It accesses the module struct data and attempts to write out module data. It is in this code path that the above BUG_ON() warning is encountered, specifically m_show() calls static char *module_flags(struct module *mod, char *buf) { int bx = 0; BUG_ON(mod->state == MODULE_STATE_UNFORMED); ... The other thread, CPU 1, in unloading the module calls the syscall delete_module() defined in kernel/module.c. The module_mutex is acquired for a short time, and then released. free_module() is called without the module_mutex. free_module() then sets mod->state = MODULE_STATE_UNFORMED, also without the module_mutex. Some additional code is called and then the module_mutex is reacquired to remove the module from the modules list: /* Now we can delete it from the lists */ mutex_lock(&module_mutex); stop_machine(__unlink_module, mod, NULL); mutex_unlock(&module_mutex); This is the sequence of events that leads to the panic. CPU 1 is removing dummy_module via delete_module(). It acquires the module_mutex, and then releases it. CPU 1 has NOT set dummy_module->state to MODULE_STATE_UNFORMED yet. CPU 0, which is reading the /proc/modules, acquires the module_mutex and acquires a pointer to the dummy_module which is still in the modules list. CPU 0 calls m_show for dummy_module. The check in m_show() for MODULE_STATE_UNFORMED passed for dummy_module even though it is being torn down. Meanwhile CPU 1, which has been continuing to remove dummy_module without holding the module_mutex, now calls free_module() and sets dummy_module->state to MODULE_STATE_UNFORMED. CPU 0 now calls module_flags() with dummy_module and ... static char *module_flags(struct module *mod, char *buf) { int bx = 0; BUG_ON(mod->state == MODULE_STATE_UNFORMED); and BOOM. Acquire and release the module_mutex lock around the setting of MODULE_STATE_UNFORMED in the teardown path, which should resolve the problem. Testing: In the unpatched kernel I can panic the system within 1 minute by doing while (true) do insmod dummy_module.ko; rmmod dummy_module.ko; done and while (true) do cat /proc/modules; done in separate terminals. In the patched kernel I was able to run just over one hour without seeing any issues. I also verified the output of panic via sysrq-c and the output of /proc/modules looks correct for all three states for the dummy_module. dummy_module 12661 0 - Unloading 0xffffffffa03a5000 (OE-) dummy_module 12661 0 - Live 0xffffffffa03bb000 (OE) dummy_module 14015 1 - Loading 0xffffffffa03a5000 (OE+) Signed-off-by: Prarit Bhargava <prarit@redhat.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org