linux-kernel - [PATCH 4.15 158/202] kernel/relay.c: revert "kernel/relay.c: fix potential memory leak"

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Message-Id: <20180215151721.162546627@linuxfoundation.org>
Date:   Thu, 15 Feb 2018 16:17:38 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>,
        syzbot <syzkaller@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zhouyi Zhou <yizhouzhou@....ac.cn>,
        Jens Axboe <axboe@...nel.dk>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.15 158/202] kernel/relay.c: revert "kernel/relay.c: fix potential memory leak"

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

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

From: Eric Biggers <ebiggers@...gle.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@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Zhouyi Zhou <yizhouzhou@....ac.cn>
Cc: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);