Messages in this thread Patch in this message | | | From | Sonny Rao <> | Subject | [PATCH] Fix infinite loop in ARM user perf_event backtrace code | Date | Fri, 15 Apr 2011 20:27:25 -0700 |
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The ARM user backtrace code can get into an infinite loop if it runs into an invalid stack frame which points back to itself. This situation has been observed in practice. Fix it by capping the number of entries in the backtrace. This is also what other architectures do in their backtrace code.
Signed-off-by: Sonny Rao <sonnyrao@chromium.org> --- arch/arm/kernel/perf_event.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index 69cfee0..1e61d60 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -746,7 +746,8 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) tail = (struct frame_tail __user *)regs->ARM_fp - 1; - while (tail && !((unsigned long)tail & 0x3)) + while ((entry->nr < PERF_MAX_STACK_DEPTH) && + tail && !((unsigned long)tail & 0x3)) tail = user_backtrace(tail, entry); } -- 1.7.3.1
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