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@I-love.SAKURA.ne.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index f28e937320a3b453371143a035e6967482d17cd4..216ab915dd54d4ad7f205aac9f0ab3e3291a2684 100644 (file)
--- 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) {