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Commit e1e23bb0 authored by David Rientjes's avatar David Rientjes Committed by Ingo Molnar
Browse files

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: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent fd048088

arch/x86/kernel/process_64.c

+2 −2
Original line number Diff line number Diff line
@@ -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))