From f7d27c35ddff7c100d7a98db499ac0040149ac05 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Mon, 19 Oct 2015 11:37:18 +0300 Subject: [PATCH] x86/mm, kasan: Silence KASAN warnings in get_wchan() 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 Signed-off-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrew Morton Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Denys Vlasenko Cc: Dmitry Vyukov Cc: Kostya Serebryany Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Wolfram Gloger Cc: kasan-dev Link: http://lkml.kernel.org/r/1445243838-17763-3-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/process.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 39e585a554b7..e28db181e4fc 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -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; }