Commit ee9397a6 authored Jul 27, 2015 by Ben Hutchings Committed by Ingo Molnar Aug 12, 2015

perf: Fix double-free of the AUX buffer



If rb->aux_refcount is decremented to zero before rb->refcount,
__rb_free_aux() may be called twice resulting in a double free of
rb->aux_pages.  Fix this by adding a check to __rb_free_aux().

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 57ffc5ca ("perf: Fix AUX buffer refcounting")
Link: http://lkml.kernel.org/r/1437953468.12842.17.camel@decadent.org.uk


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

parent fed66e2c

kernel/events/ring_buffer.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -559,12 +559,14 @@ static void __rb_free_aux(struct ring_buffer *rb)
		rb->aux_priv = NULL;
		}

		if (rb->aux_nr_pages) {
		for (pg = 0; pg < rb->aux_nr_pages; pg++)
		rb_free_aux_page(rb, pg);

		kfree(rb->aux_pages);
		rb->aux_nr_pages = 0;
		}
		}

		void rb_free_aux(struct ring_buffer *rb)
		{