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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, David Herrmann <dh.herrmann@gmail.com>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 021/114] net: drop write-only stack variable
Date:   Thu,  8 Nov 2018 13:50:36 -0800
Message-Id: <20181108215101.046481417@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit 3575dbf2cbbc8e598f17ec441aed526dbea0e1bd ]

Remove a write-only stack variable from unix_attach_fds(). This is a
left-over from the security fix in:

    commit 712f4aad406bb1ed67f3f98d04c044191f0ff593
    Author: willy tarreau <w@1wt.eu>
    Date:   Sun Jan 10 07:54:56 2016 +0100

        unix: properly account for FDs passed over unix sockets

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/unix/af_unix.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e05ec54ac53f..c6b1eec94911 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1531,7 +1531,6 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 {
 	int i;
 	unsigned char max_level = 0;
-	int unix_sock_count = 0;
 
 	if (too_many_unix_fds(current))
 		return -ETOOMANYREFS;
@@ -1539,11 +1538,9 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 	for (i = scm->fp->count - 1; i >= 0; i--) {
 		struct sock *sk = unix_get_socket(scm->fp->fp[i]);
 
-		if (sk) {
-			unix_sock_count++;
+		if (sk)
 			max_level = max(max_level,
 					unix_sk(sk)->recursion_level);
-		}
 	}
 	if (unlikely(max_level > MAX_RECURSION_LEVEL))
 		return -ETOOMANYREFS;
-- 
2.17.1