DivestOS/Patches/Linux_CVEs/CVE-2016-3768/ANY/0.patch
2017-10-29 22:14:37 -04:00

53 lines
2.2 KiB
Diff

From 84d8c81420aaa7c6cd6f57cb52daccf07b1f7a50 Mon Sep 17 00:00:00 2001
From: Veena Sambasivan <veenas@codeaurora.org>
Date: Thu, 19 May 2016 18:47:15 -0700
Subject: [PATCH] msm: perf: Do not allocate new hw_event if event is
duplicate.
During a perf_event_enable, kernel/events/core.c calls pmu->add() which
is platform implementation(arch/arm/kernel/perf_event.c). Due to the
duplicate constraints, arch/arm/mach-msm/perf_event_msm_krait_l2.c
drivers marks the event as OFF but returns TRUE to perf_event.c which
goes ahead and allocates the hw_event and enables it.
Since event is marked OFF, kernel events core will try to enable this event
again during next perf_event_enable. Which results in same event enabled
on multiple hw_events. But during the perf_release, event struct is freed
and only one hw_event is released. This results in dereferencing the
invalid pointer and hence the crash.
Fix this by returning error in case of constraint event duplicate. Hence
avoiding the same event programmed on multiple hw event counters.
bug: 28172137
Change-Id: Ia3360be027dfe87ac753191ffe7e0bc947e72455
Signed-off-by: Arun KS <arunks@codeaurora.org>
Signed-off-by: Veena Sambasivan <veenas@codeaurora.org>
---
arch/arm/kernel/perf_event.c | 1 +
arch/arm/mach-msm/perf_event_msm_krait_l2.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 0f288a7c035f9..a0c1e318a7905 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -240,6 +240,7 @@ armpmu_add(struct perf_event *event, int flags)
pr_err("Event: %llx failed constraint check.\n",
event->attr.config);
event->state = PERF_EVENT_STATE_OFF;
+ err = -EPERM;
goto out;
}
diff --git a/arch/arm/mach-msm/perf_event_msm_krait_l2.c b/arch/arm/mach-msm/perf_event_msm_krait_l2.c
index 65a5d2f8e1bcd..cc39b719b33fb 100644
--- a/arch/arm/mach-msm/perf_event_msm_krait_l2.c
+++ b/arch/arm/mach-msm/perf_event_msm_krait_l2.c
@@ -468,6 +468,7 @@ static int msm_l2_test_set_ev_constraint(struct perf_event *event)
if (!(event->cpu < 0)) {
event->state = PERF_EVENT_STATE_OFF;
event->attr.constraint_duplicate = 1;
+ err = -EPERM;
}
}
out: