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perf/core: make account/unaccount_sb_event consistent

PATCH In review David Carrillo-Cisneros 3 participants 3 messages Jun 1, 2016 – Jun 8, 2016 perf events

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David Carrillo-Cisneros

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#0 lore raw

PATCH 1/1 perf/core: make account/unaccount_sb_event consistent

unaccount_pmu_sb_event did not check for attributes in event->attr before calling detach_sb_event, while account_pmu_event did.

This caused NULL pointer reference in cgroup events that did not have any of the attributes checked by account_pmu_event.

To trigger the bug just wait for a cgroup event to terminate, e.g.:

$ mkdir /dev/cgroup/devices/test
$ perf stat -e cycles -a -G test sleep 0

... see crash ...

Patch rebased on peterz/queue/perf/core .

Reviewed-by Stephane Eranian <[email protected]>
Signed-off-by David Carrillo-Cisneros <[email protected]>
---
 kernel/events/core.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)
kernel/events/core.c +18 -16
index 1e48efc..6af0f01 100644
@@ -3682,15 +3682,28 @@ static void detach_sb_event(struct perf_event *event)
 	raw_spin_unlock(&pel->lock);
 }
 
-static void unaccount_pmu_sb_event(struct perf_event *event)
+static bool is_sb_event(struct perf_event *event)
 {
+	struct perf_event_attr *attr = &event->attr;
+
 	if (event->parent)
-		return;
+		return false;
 
 	if (event->attach_state & PERF_ATTACH_TASK)
-		return;
+		return false;
 
-	detach_sb_event(event);
+	if (attr->mmap || attr->mmap_data || attr->mmap2 ||
+	    attr->comm || attr->comm_exec ||
+	    attr->task ||
+	    attr->context_switch)
+		return true;
+	return false;
+}
+
+static void unaccount_pmu_sb_event(struct perf_event *event)
+{
+	if (is_sb_event(event))
+		detach_sb_event(event);
 }
 
 static void unaccount_event_cpu(struct perf_event *event, int cpu)

@@ -8666,18 +8679,7 @@ static void attach_sb_event(struct perf_event *event)
  */
 static void account_pmu_sb_event(struct perf_event *event)
 {
-	struct perf_event_attr *attr = &event->attr;
-
-	if (event->parent)
-		return;
-
-	if (event->attach_state & PERF_ATTACH_TASK)
-		return;
-
-	if (attr->mmap || attr->mmap_data || attr->mmap2 ||
-	    attr->comm || attr->comm_exec ||
-	    attr->task ||
-	    attr->context_switch)
+	if (is_sb_event(event))
 		attach_sb_event(event);
 }
Signature · 1 line
2.8.0.rc3.226.g39d4020
Tested-by on v1 1/1
#1 lore raw
Quoted 13 lines · David Carrillo-Cisneros

unaccount_pmu_sb_event did not check for attributes in event->attr before calling detach_sb_event, while account_pmu_event did.

This caused NULL pointer reference in cgroup events that did not have any of the attributes checked by account_pmu_event.

To trigger the bug just wait for a cgroup event to terminate, e.g.:

$ mkdir /dev/cgroup/devices/test
$ perf stat -e cycles -a -G test sleep 0

... see crash ...

Quoted 7 lines

Patch rebased on peterz/queue/perf/core .

Reviewed-by Stephane Eranian <[email protected]>
Signed-off-by David Carrillo-Cisneros <[email protected]>
---
 kernel/events/core.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)
Tested-by Borislav Petkov <[email protected]>
Signature · 4 lines
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
merge bot
#2 lore raw

[tip:perf/core] perf/core: Fix crash due to account/unaccount_sb_event() inconsistency

In reply to David Carrillo-Cisneros
perf/core: Fix crash due to account/unaccount_sb_event() inconsistency
Commit-ID:  a4f144ebbdf6f7807c477bce8e136047ed27321f
Gitweb:     http://git.kernel.org/tip/a4f144ebbdf6f7807c477bce8e136047ed27321f
Author:     David Carrillo-Cisneros <[email protected]>
AuthorDate: Wed, 1 Jun 2016 12:33:05 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 8 Jun 2016 09:18:45 +0200

perf/core: Fix crash due to account/unaccount_sb_event() inconsistency

unaccount_pmu_sb_event() did not check for attributes in event->attr before calling detach_sb_event(), while account_pmu_event() did.

This caused NULL pointer reference in cgroup events that did not have any of the attributes checked by account_pmu_event().

To trigger the bug just wait for a cgroup event to terminate, e.g.:

  $ mkdir /dev/cgroup/devices/test
  $ perf stat -e cycles -a -G test sleep 0

... see crash ...

Signed-off-by David Carrillo-Cisneros <[email protected]>
Reviewed-by Stephane Eranian <[email protected]>
Cc Alexander Shishkin <[email protected]>
Cc Arnaldo Carvalho de Melo <[email protected]>
Cc Jiri Olsa <[email protected]>
Cc Kan Liang <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc Zheng <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 kernel/events/core.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)
kernel/events/core.c +18 -16
index 5d48306..ae081a1 100644
@@ -3682,15 +3682,28 @@ static void detach_sb_event(struct perf_event *event)
 	raw_spin_unlock(&pel->lock);
 }
 
-static void unaccount_pmu_sb_event(struct perf_event *event)
+static bool is_sb_event(struct perf_event *event)
 {
+	struct perf_event_attr *attr = &event->attr;
+
 	if (event->parent)
-		return;
+		return false;
 
 	if (event->attach_state & PERF_ATTACH_TASK)
-		return;
+		return false;
 
-	detach_sb_event(event);
+	if (attr->mmap || attr->mmap_data || attr->mmap2 ||
+	    attr->comm || attr->comm_exec ||
+	    attr->task ||
+	    attr->context_switch)
+		return true;
+	return false;
+}
+
+static void unaccount_pmu_sb_event(struct perf_event *event)
+{
+	if (is_sb_event(event))
+		detach_sb_event(event);
 }
 
 static void unaccount_event_cpu(struct perf_event *event, int cpu)

@@ -8666,18 +8679,7 @@ static void attach_sb_event(struct perf_event *event)
  */
 static void account_pmu_sb_event(struct perf_event *event)
 {
-	struct perf_event_attr *attr = &event->attr;
-
-	if (event->parent)
-		return;
-
-	if (event->attach_state & PERF_ATTACH_TASK)
-		return;
-
-	if (attr->mmap || attr->mmap_data || attr->mmap2 ||
-	    attr->comm || attr->comm_exec ||
-	    attr->task ||
-	    attr->context_switch)
+	if (is_sb_event(event))
 		attach_sb_event(event);
 }