[PATCH 4.9 63/88] kernel/relay.c: revert "kernel/relay.c: fix potential memory leak"

[Greg Kroah-Hartman]

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

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

From: Eric Biggers <ebigg...@google.com>

commit a1be1f3931bfe0a42b46fef77a04593c2b136e7f upstream.

This reverts commit ba62bafe942b ("kernel/relay.c: fix potential memory leak").

This commit introduced a double free bug, because 'chan' is already
freed by the line:

    kref_put(&chan->kref, relay_destroy_channel);

This bug was found by syzkaller, using the BLKTRACESETUP ioctl.

Link: http://lkml.kernel.org/r/20180127004759.101823-1-ebigge...@gmail.com
Fixes: ba62bafe942b ("kernel/relay.c: fix potential memory leak")
Signed-off-by: Eric Biggers <ebigg...@google.com>
Reported-by: syzbot <syzkal...@googlegroups.com>
Reviewed-by: Andrew Morton <a...@linux-foundation.org>
Cc: Zhouyi Zhou <yizhouz...@ict.ac.cn>
Cc: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 kernel/relay.c |    1 -
 1 file changed, 1 deletion(-)

--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -611,7 +611,6 @@ free_bufs:
 
        kref_put(&chan->kref, relay_destroy_channel);
        mutex_unlock(&relay_channels_mutex);
-       kfree(chan);
        return NULL;
 }
 EXPORT_SYMBOL_GPL(relay_open);