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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: 57ffc5ca67 ("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>
This commit is contained in:
Ben Hutchings 2015-07-27 00:31:08 +01:00 committed by Ingo Molnar
parent fed66e2cdd
commit ee9397a6fb
1 changed files with 6 additions and 4 deletions
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10
kernel/events/ring_buffer.c
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@ -559,11 +559,13 @@ static void __rb_free_aux(struct ring_buffer *rb)
rb->aux_priv = NULL;
}
for (pg = 0; pg < rb->aux_nr_pages; pg++)
rb_free_aux_page(rb, pg);
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;
kfree(rb->aux_pages);
rb->aux_nr_pages = 0;
}
}
void rb_free_aux(struct ring_buffer *rb)