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x86: avoid dereferencing beyond stack + THREAD_SIZE

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It's possible for get_wchan() to dereference past task->stack + THREAD_SIZE
while iterating through instruction pointers if fp equals the upper boundary,
causing a kernel panic.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
David Rientjes 2008-10-07 14:15:11 -07:00 committed by Ingo Molnar
parent fd04808830
commit e1e23bb051
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kernel/process_64.c
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@ -754,12 +754,12 @@ unsigned long get_wchan(struct task_struct *p)
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
stack = (unsigned long)task_stack_page(p);
if (p->thread.sp < stack || p->thread.sp > stack+THREAD_SIZE)
if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
return 0;
fp = *(u64 *)(p->thread.sp);
do {
if (fp < (unsigned long)stack ||
fp > (unsigned long)stack+THREAD_SIZE)
fp >= (unsigned long)stack+THREAD_SIZE)
return 0;
ip = *(u64 *)(fp+8);
if (!in_sched_functions(ip))