From mboxrd@z Thu Jan 1 00:00:00 1970 From: k.khlebnikov@samsung.com (Konstantin Khlebnikov) Date: Thu, 05 Dec 2013 17:30:10 +0400 Subject: [PATCH 1/2] ARM64: check stack pointer in get_wchan Message-ID: <20131205133010.16410.96824.stgit@buzz> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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: Konstantin Khlebnikov --- arch/arm64/kernel/process.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index de17c89..0adb8f0 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -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;