x86: avoid dereferencing beyond stack + THREAD_SIZE
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>
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@ -754,12 +754,12 @@ unsigned long get_wchan(struct task_struct *p)
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if (!p || p == current || p->state == TASK_RUNNING)
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return 0;
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stack = (unsigned long)task_stack_page(p);
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if (p->thread.sp < stack || p->thread.sp > stack+THREAD_SIZE)
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if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
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return 0;
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fp = *(u64 *)(p->thread.sp);
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do {
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if (fp < (unsigned long)stack ||
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fp > (unsigned long)stack+THREAD_SIZE)
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fp >= (unsigned long)stack+THREAD_SIZE)
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return 0;
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ip = *(u64 *)(fp+8);
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if (!in_sched_functions(ip))
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