This is a note to let you know that I've just added the patch titled
ARM: 7809/1: perf: fix event validation for software group leaders
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-7809-1-perf-fix-event-validation-for-software-group-leaders.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c95eb3184ea1a3a2551df57190c81da695e2144b Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@xxxxxxx>
Date: Wed, 7 Aug 2013 23:39:41 +0100
Subject: ARM: 7809/1: perf: fix event validation for software group leaders
From: Will Deacon <will.deacon@xxxxxxx>
commit c95eb3184ea1a3a2551df57190c81da695e2144b upstream.
It is possible to construct an event group with a software event as a
group leader and then subsequently add a hardware event to the group.
This results in the event group being validated by adding all members
of the group to a fake PMU and attempting to allocate each event on
their respective PMU.
Unfortunately, for software events wthout a corresponding arm_pmu, this
results in a kernel crash attempting to dereference the ->get_event_idx
function pointer.
This patch fixes the problem by checking explicitly for software events
and ignoring those in event validation (since they can always be
scheduled). We will probably want to revisit this for 3.12, since the
validation checks don't appear to work correctly when dealing with
multiple hardware PMUs anyway.
Reported-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Tested-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/perf_event.c | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -324,6 +324,9 @@ validate_event(struct pmu_hw_events *hw_
struct hw_perf_event fake_event = event->hw;
struct pmu *leader_pmu = event->group_leader->pmu;
+ if (is_software_event(event))
+ return 1;
+
if (event->pmu != leader_pmu || event->state < PERF_EVENT_STATE_OFF)
return 1;
Patches currently in stable-queue which might be from will.deacon@xxxxxxx are
queue-3.4/alpha-makefile-don-t-enforce-small-data-model-for-kernel-builds.patch
queue-3.4/arm-7809-1-perf-fix-event-validation-for-software-group-leaders.patch
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