4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@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-ebiggers3@gmail.com Fixes: ba62bafe942b ("kernel/relay.c: fix potential memory leak") Signed-off-by: Eric Biggers ebiggers@google.com Reported-by: syzbot syzkaller@googlegroups.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Zhouyi Zhou yizhouzhou@ict.ac.cn Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@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);