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x86/mm, kasan: Silence KASAN warnings in get_wchan()

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get_wchan() is racy by design, it may access volatile stack
of running task, thus it may access redzone in a stack frame
and cause KASAN to warn about this.

Use READ_ONCE_NOCHECK() to silence these warnings.

Reported-by: Sasha Levin <[email protected]>
Signed-off-by: Andrey Ryabinin <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Kostya Serebryany <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wolfram Gloger <[email protected]>
Cc: kasan-dev <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Andrey Ryabinin authored and Ingo Molnar committed 2015-10-20 11:04:19 +02:00
1 parent d976441f44
commit f7d27c35dd
1 file changed
+3 -3
Download Patch File Download Diff File Expand all files Collapse all files
arch/x86/kernel/process.c
+3 -3
View File
@@ -550,14 +550,14 @@ unsigned long get_wchan(struct task_struct *p)
if (sp < bottom || sp > top)
return 0;
fp = READ_ONCE(*(unsigned long *)sp);
fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
do {
if (fp < bottom || fp > top)
return 0;
ip = READ_ONCE(*(unsigned long *)(fp + sizeof(unsigned long)));
ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
if (!in_sched_functions(ip))
return ip;
fp = READ_ONCE(*(unsigned long *)fp);
fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
} while (count++ < 16 && p->state != TASK_RUNNING);
return 0;
}