Commit 059fcd8c authored Feb 09, 2016 by Thomas Gleixner Committed by Ingo Molnar Feb 17, 2016

perf/core: Plug potential memory leak in CPU_UP_PREPARE



If CPU_UP_PREPARE is called it is not guaranteed, that a previously allocated
and assigned hash has been freed already, but perf_event_init_cpu()
unconditionally allocates and assignes a new hash if the swhash is referenced.
By overwriting the pointer the existing hash is not longer accessible.

Verify that there is no hash assigned on this cpu before allocating and
assigning a new one.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.843269966@linutronix.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 27ca9236

kernel/events/core.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -9206,7 +9206,7 @@ static void perf_event_init_cpu(int cpu)
		struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);

		mutex_lock(&swhash->hlist_mutex);
		if (swhash->hlist_refcount > 0) {
		if (swhash->hlist_refcount > 0 && !swevent_hlist_deref(swhash)) {
		struct swevent_hlist *hlist;

		hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));

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