[PATCHv2] ARM: perf/oprofile: fix off-by-one in stack check
From: Rabin Vincent <hidden>
Date: 2011-02-09 03:56:07
Subsystem:
arm pmu profiling and debugging, arm port, performance events subsystem, the rest · Maintainers:
Will Deacon, Mark Rutland, Russell King, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
Since tail is the previous fp - 1, we need to compare the new fp with tail + 1 to ensure that we don't end up passing in the same tail again, in order to avoid a potential infinite loop in the perf interrupt handler (which has been observed to occur). A similar fix seems to be needed in the OProfile code. Signed-off-by: Rabin Vincent <redacted> --- v2: refined check as per Will's comment arch/arm/kernel/perf_event.c | 2 +- arch/arm/oprofile/common.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 5efa264..d150ad1 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c@@ -700,7 +700,7 @@ user_backtrace(struct frame_tail __user *tail, * Frame pointers should strictly progress back up the stack * (towards higher addresses). */ - if (tail >= buftail.fp) + if (tail + 1 >= buftail.fp) return NULL; return buftail.fp - 1;
diff --git a/arch/arm/oprofile/common.c b/arch/arm/oprofile/common.c
index 8aa9744..6adda2b 100644
--- a/arch/arm/oprofile/common.c
+++ b/arch/arm/oprofile/common.c@@ -85,7 +85,7 @@ static struct frame_tail* user_backtrace(struct frame_tail *tail) /* frame pointers should strictly progress back up the stack * (towards higher addresses) */ - if (tail >= buftail[0].fp) + if (tail + 1 >= buftail[0].fp) return NULL; return buftail[0].fp-1;
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1.7.2.dirty