netlink: make sure nladdr has correct size in netlink_connect()

KMSAN reports use of uninitialized memory in the case when |alen| is
smaller than sizeof(struct sockaddr_nl), and therefore |nladdr| isn't
fully copied from the userspace.

Signed-off-by: Alexander Potapenko <glider@google.com>
Fixes: 1da177e4c3f41524 ("Linux-2.6.12-rc2")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 07e8478..70c4553 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1085,6 +1085,9 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
        if (addr->sa_family != AF_NETLINK)
                return -EINVAL;
 
+       if (alen < sizeof(struct sockaddr_nl))
+               return -EINVAL;
+
        if ((nladdr->nl_groups || nladdr->nl_pid) &&
            !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
                return -EPERM;