netdev - [PATCH 4/9] net: netlink: Check address length before reading groups field

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Message-Id: <1555066418-9445-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
Date:   Fri, 12 Apr 2019 19:53:38 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Subject: [PATCH 4/9] net: netlink: Check address length before reading groups field

KMSAN will complain if valid address length passed to bind() is shorter
than sizeof(struct sockaddr_nl) bytes.

Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 net/netlink/af_netlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index f28e937320a3..216ab915dd54 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -988,7 +988,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 	struct netlink_sock *nlk = nlk_sk(sk);
 	struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 	int err = 0;
-	unsigned long groups = nladdr->nl_groups;
+	unsigned long groups;
 	bool bound;
 
 	if (addr_len < sizeof(struct sockaddr_nl))
@@ -996,6 +996,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 
 	if (nladdr->nl_family != AF_NETLINK)
 		return -EINVAL;
+	groups = nladdr->nl_groups;
 
 	/* Only superuser is allowed to listen multicasts */
 	if (groups) {
-- 
2.16.5