linux-kernel - [PATCH 2.6.32 16/55] af_unix: fix struct pid memory leak

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Message-Id: <20160304153001.410771397@1wt.eu>
Date:	Fri, 04 Mar 2016 16:30:16 +0100
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Rainer Weikusat <rweikusat@...ileactivedefense.com>,
	"David S. Miller" <davem@...emloft.net>,
	Ben Hutchings <ben@...adent.org.uk>, Willy Tarreau <w@....eu>
Subject: [PATCH 2.6.32 16/55] af_unix: fix struct pid memory leak

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

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

From: Eric Dumazet <edumazet@...gle.com>

commit fa0dc04df259ba2df3ce1920e9690c7842f8fa4b upstream.

Dmitry reported a struct pid leak detected by a syzkaller program.

Bug happens in unix_stream_recvmsg() when we break the loop when a
signal is pending, without properly releasing scm.

Fixes: b3ca9b02b007 ("net: fix multithreaded signal handling in unix recv routines")
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Rainer Weikusat <rweikusat@...ileactivedefense.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Cc: Ben Hutchings <ben@...adent.org.uk>
[wt: note, according to Rainer & Ben the bug was really introduced in
 2.5.65, not by the commit mentionned in Fixes. 2.6.32 uses siocb->scm
 instead of scm]
Signed-off-by: Willy Tarreau <w@....eu>
---
 net/unix/af_unix.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 8e6a609..67f50be 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2018,6 +2018,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
 
 			if (signal_pending(current)) {
 				err = sock_intr_errno(timeo);
+				scm_destroy(siocb->scm);
 				goto out;
 			}
 			mutex_lock(&u->readlock);
-- 
1.7.12.2.21.g234cd45.dirty