diff options
| author | Vinayak Menon <vinayakm.list@gmail.com> | 2014-06-02 18:17:59 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-08 15:42:06 -0700 |
| commit | ddac7d5fba555967654bf47b7b458b050391dc1f (patch) | |
| tree | 0364c7745c4b9ee18b93f793a370aab44d59f94c /drivers/staging/android | |
| parent | 5b796fe8fc8d534747151d8b8bbc8e2547ce68cd (diff) | |
staging: binder: add vm_fault handler
An issue was observed when a userspace task exits.
The page which hits error here is the zero page.
In binder mmap, the whole of vma is not mapped.
On a task crash, when debuggerd reads the binder regions,
the unmapped areas fall to do_anonymous_page in handle_pte_fault,
due to the absence of a vm_fault handler. This results in
zero page being mapped. Later in zap_pte_range, vm_normal_page
returns zero page in the case of VM_MIXEDMAP and it results in the
error.
BUG: Bad page map in process mediaserver pte:9dff379f pmd:9bfbd831
page:c0ed8e60 count:1 mapcount:-1 mapping: (null) index:0x0
page flags: 0x404(referenced|reserved)
addr:40c3f000 vm_flags:10220051 anon_vma: (null) mapping:d9fe0764 index:fd
vma->vm_ops->fault: (null)
vma->vm_file->f_op->mmap: binder_mmap+0x0/0x274
CPU: 0 PID: 1463 Comm: mediaserver Tainted: G W 3.10.17+ #1
[<c001549c>] (unwind_backtrace+0x0/0x11c) from [<c001200c>] (show_stack+0x10/0x14)
[<c001200c>] (show_stack+0x10/0x14) from [<c0103d78>] (print_bad_pte+0x158/0x190)
[<c0103d78>] (print_bad_pte+0x158/0x190) from [<c01055f0>] (unmap_single_vma+0x2e4/0x598)
[<c01055f0>] (unmap_single_vma+0x2e4/0x598) from [<c010618c>] (unmap_vmas+0x34/0x50)
[<c010618c>] (unmap_vmas+0x34/0x50) from [<c010a9e4>] (exit_mmap+0xc8/0x1e8)
[<c010a9e4>] (exit_mmap+0xc8/0x1e8) from [<c00520f0>] (mmput+0x54/0xd0)
[<c00520f0>] (mmput+0x54/0xd0) from [<c005972c>] (do_exit+0x360/0x990)
[<c005972c>] (do_exit+0x360/0x990) from [<c0059ef0>] (do_group_exit+0x84/0xc0)
[<c0059ef0>] (do_group_exit+0x84/0xc0) from [<c0066de0>] (get_signal_to_deliver+0x4d4/0x548)
[<c0066de0>] (get_signal_to_deliver+0x4d4/0x548) from [<c0011500>] (do_signal+0xa8/0x3b8)
Add a vm_fault handler which returns VM_FAULT_SIGBUS, and prevents the
wrong fallback to do_anonymous_page.
Signed-off-by: Vinayak Menon <vinayakm.list@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/android')
| -rw-r--r-- | drivers/staging/android/binder.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c index 589cfc81f419..2f38e44ce44b 100644 --- a/drivers/staging/android/binder.c +++ b/drivers/staging/android/binder.c @@ -2768,9 +2768,15 @@ static void binder_vma_close(struct vm_area_struct *vma) binder_defer_work(proc, BINDER_DEFERRED_PUT_FILES); } +static int binder_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + return VM_FAULT_SIGBUS; +} + static struct vm_operations_struct binder_vm_ops = { .open = binder_vma_open, .close = binder_vma_close, + .fault = binder_vm_fault, }; static int binder_mmap(struct file *filp, struct vm_area_struct *vma) |