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

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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 <davidcc@google.com>
Reviewed-by: Stephane Eranian <eranian@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Zheng <zheng.z.yan@intel.com>
Link: http://lkml.kernel.org/r/1464809585-66072-1-git-send-email-davidcc@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
David Carrillo-Cisneros 2016-06-01 12:33:05 -07:00 committed by Ingo Molnar
parent 030ba6cd10
commit a4f144ebbd
1 changed files with 18 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
kernel/events/core.c
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@ -3682,15 +3682,28 @@ static void detach_sb_event(struct perf_event *event)
raw_spin_unlock(&pel->lock); 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) if (event->parent)
return; return false;
if (event->attach_state & PERF_ATTACH_TASK) 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) 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) static void account_pmu_sb_event(struct perf_event *event)
{ {
struct perf_event_attr *attr = &event->attr; if (is_sb_event(event))
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)
attach_sb_event(event); attach_sb_event(event);
} }