linux-kernel - [PATCH 4.4 119/137] perf: Do not double free

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Date:	Mon, 18 Apr 2016 11:29:41 +0900
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>, dvyukov@...gle.com,
	eranian@...gle.com, oleg@...hat.com, panand@...hat.com,
	sasha.levin@...cle.com, vince@...ter.net,
	Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.4 119/137] perf: Do not double free

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz@...radead.org>

commit 130056275ade730e7a79c110212c8815202773ee upstream.

In case of: err_file: fput(event_file), we'll end up calling
perf_release() which in turn will free the event.

Do not then free the event _again_.

Tested-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: dvyukov@...gle.com
Cc: eranian@...gle.com
Cc: oleg@...hat.com
Cc: panand@...hat.com
Cc: sasha.levin@...cle.com
Cc: vince@...ter.net
Link: http://lkml.kernel.org/r/20160224174947.697350349@infradead.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/events/core.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8583,7 +8583,12 @@ err_context:
 	perf_unpin_context(ctx);
 	put_ctx(ctx);
 err_alloc:
-	free_event(event);
+	/*
+	 * If event_file is set, the fput() above will have called ->release()
+	 * and that will take care of freeing the event.
+	 */
+	if (!event_file)
+		free_event(event);
 err_cpus:
 	put_online_cpus();
 err_task: