diff options
| author | Vasily Gorbik <gor@linux.ibm.com> | 2019-08-13 20:11:08 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2019-08-21 12:58:52 +0200 |
| commit | 8769f610fe6d473e5e8e221709c3ac402037da6c (patch) | |
| tree | c740258be7d3cd1f37d7c58d4495d7b11af31ce9 | |
| parent | f45f7b5bdaa4828ce871cf03f7c01599a0de57a5 (diff) | |
s390/process: avoid potential reading of freed stack
With THREAD_INFO_IN_TASK (which is selected on s390) task's stack usage
is refcounted and should always be protected by get/put when touching
other task's stack to avoid race conditions with task's destruction code.
Fixes: d5c352cdd022 ("s390: move thread_info into task_struct")
Cc: stable@vger.kernel.org # v4.10+
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/kernel/process.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 63873aa6693f..9f2727bf3cbe 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -184,20 +184,30 @@ unsigned long get_wchan(struct task_struct *p) if (!p || p == current || p->state == TASK_RUNNING || !task_stack_page(p)) return 0; + + if (!try_get_task_stack(p)) + return 0; + low = task_stack_page(p); high = (struct stack_frame *) task_pt_regs(p); sf = (struct stack_frame *) p->thread.ksp; - if (sf <= low || sf > high) - return 0; + if (sf <= low || sf > high) { + return_address = 0; + goto out; + } for (count = 0; count < 16; count++) { sf = (struct stack_frame *) sf->back_chain; - if (sf <= low || sf > high) - return 0; + if (sf <= low || sf > high) { + return_address = 0; + goto out; + } return_address = sf->gprs[8]; if (!in_sched_functions(return_address)) - return return_address; + goto out; } - return 0; +out: + put_task_stack(p); + return return_address; } unsigned long arch_align_stack(unsigned long sp) |