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| author | Konstantin Khlebnikov <k.khlebnikov@samsung.com> | 2013-12-05 14:21:36 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-12-09 23:24:31 +0000 |
| commit | 1b15ec7a7427d4188ba91b9bbac696250a059d22 (patch) | |
| tree | 1f5db8d672dbfb84078ef6814f2bc3aed2937a02 /arch/arm | |
| parent | 7c927322d349e37eef38d121c6f596ba816a40b2 (diff) | |
| download | linux-1b15ec7a7427d4188ba91b9bbac696250a059d22.tar.bz2 | |
ARM: 7912/1: 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.
/proc/$pid/stack interface had been disabled for non-current tasks, see [1]
But 'wchan' still allows to trigger stack frame unwinding on volatile stack.
This patch fixes oops in unwind_frame() by adding stack pointer validation on
each step (as x86 code do), unwind_frame() already checks frame pointer.
Also I've found another report of this oops on stackoverflow (irony).
Link: http://www.spinics.net/lists/arm-kernel/msg110589.html [1]
Link: http://stackoverflow.com/questions/18479894/unwind-frame-cause-a-kernel-paging-error
Cc: <stable@vger.kernel.org>
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/process.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 94f6b05f9e24..92f7b15dd221 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -404,6 +404,7 @@ EXPORT_SYMBOL(dump_fpu); 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; @@ -412,9 +413,11 @@ unsigned long get_wchan(struct task_struct *p) frame.sp = thread_saved_sp(p); frame.lr = 0; /* recovered from the stack */ 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) < 0) return 0; if (!in_sched_functions(frame.pc)) return frame.pc; |