Patch "drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmu" has been added to the 4.6-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmu

to the 4.6-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:
     drivers-perf-arm_pmu-defer-the-setting-of-__oprofile_cpu_pmu.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0f254c7671e851243412bce6c2e618732831d0f8 Mon Sep 17 00:00:00 2001
From: Julien Grall <julien.grall@arm.com>
Date: Tue, 31 May 2016 12:41:22 +0100
Subject: drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmu

From: Julien Grall <julien.grall@arm.com>

commit 0f254c7671e851243412bce6c2e618732831d0f8 upstream.

The global variable __oprofile_cpu_pmu is set before the PMU is fully
initialized. If an error occurs before the end of the initialization,
the PMU will be freed and the variable will contain an invalid pointer.

This will result in a kernel crash when perf will be used.

Fix it by moving the setting of __oprofile_cpu_pmu when the PMU is fully
initialized (i.e when it is no longer possible to fail).

Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/perf/arm_pmu.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -987,9 +987,6 @@ int arm_pmu_device_probe(struct platform
 
 	armpmu_init(pmu);
 
-	if (!__oprofile_cpu_pmu)
-		__oprofile_cpu_pmu = pmu;
-
 	pmu->plat_device = pdev;
 
 	if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
@@ -1025,6 +1022,9 @@ int arm_pmu_device_probe(struct platform
 	if (ret)
 		goto out_destroy;
 
+	if (!__oprofile_cpu_pmu)
+		__oprofile_cpu_pmu = pmu;
+
 	pr_info("enabled with %s PMU driver, %d counters available\n",
 			pmu->name, pmu->num_events);
 


Patches currently in stable-queue which might be from julien.grall@arm.com are

queue-4.6/drivers-perf-arm_pmu-defer-the-setting-of-__oprofile_cpu_pmu.patch