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authorSonny Rao <sonnyrao@chromium.org>2011-04-18 22:12:59 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-04-27 22:02:46 +0100
commit860ad7823fdc00cd61dc70e7f35e07fb327cc9a4 (patch)
tree810f49eaad81ab60b4469c7c1c5203539df42acd /arch/arm/kernel/perf_event.c
parent167f829752f9cef51f59cc500abc0ad6ba69f5cb (diff)
downloadlinux-860ad7823fdc00cd61dc70e7f35e07fb327cc9a4.tar.gz
ARM: 6884/1: Fix infinite loop in ARM user perf_event backtrace code
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> Acked-by: Jamie Iles <jamie@jamieiles.com> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/perf_event.c')
-rw-r--r--arch/arm/kernel/perf_event.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 979da3947f42..139e3c827369 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);
}