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Commit 408c3658 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Catalin Marinas
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ARM64: check stack pointer in get_wchan 



get_wchan() is lockless. Task may wakeup at any time and change its own stack,
thus each next stack frame may be overwritten and filled with random stuff.

Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 50afc33a

arch/arm64/kernel/process.c

+5 −2
Original line number Diff line number Diff line
@@ -308,6 +308,7 @@ struct task_struct *__switch_to(struct task_struct *prev, 
unsigned long get_wchan(struct task_struct *p)

{

	struct stackframe frame;

	unsigned long stack_page;

	int count = 0;

	if (!p || p == current || p->state == TASK_RUNNING)

		return 0;
@@ -315,9 +316,11 @@ unsigned long get_wchan(struct task_struct *p) 
	frame.fp = thread_saved_fp(p);

	frame.sp = thread_saved_sp(p);

	frame.pc = thread_saved_pc(p);

	stack_page = (unsigned long)task_stack_page(p);

	do {

		int ret = unwind_frame(&frame);

		if (ret < 0)

		if (frame.sp < stack_page ||

		    frame.sp >= stack_page + THREAD_SIZE ||

		    unwind_frame(&frame))

			return 0;

		if (!in_sched_functions(frame.pc))

			return frame.pc;