ARM: 7356/1: perf: check that we have an event in the PMU IRQ handlers

The PMU IRQ handlers in perf assume that if a counter has overflowed
then perf must be responsible. In the paranoid world of crazy hardware,
this could be false, so check that we do have a valid event before
attempting to dereference NULL in the interrupt path.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 050cc8bf7246..4d7095af2ab3 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -960,6 +960,10 @@ static irqreturn_t armv7pmu_handle_irq(int irq_num, void *dev)
                 struct perf_event *event = cpuc->events[idx];
                 struct hw_perf_event *hwc;
 
+                /* Ignore if we don't have an event. */
+                if (!event)
+                        continue;
+
                 /*
                  * We have a single interrupt for all counters. Check that
                  * each counter has overflowed before we process it.