Patch "perf: Fix double-free of the AUX buffer" has been added to the 4.1-stable tree

Patch "perf: Fix double-free of the AUX buffer" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    perf: Fix double-free of the AUX buffer

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-fix-double-free-of-the-aux-buffer.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ee9397a6fb9bc4e52677f5e33eed4abee0f515e6 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 27 Jul 2015 00:31:08 +0100
Subject: perf: Fix double-free of the AUX buffer

From: Ben Hutchings <ben@decadent.org.uk>

commit ee9397a6fb9bc4e52677f5e33eed4abee0f515e6 upstream.

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>
Fixes: 57ffc5ca679f ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/events/ring_buffer.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -547,11 +547,13 @@ static void __rb_free_aux(struct ring_bu
 		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)


Patches currently in stable-queue which might be from ben@decadent.org.uk are

queue-4.1/perf-fix-double-free-of-the-aux-buffer.patch