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

[ Upstream commit 7880287981b60a6808f39f297bb66936e8bdf57a ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index c1f59a06da6f2d14c0e4f19b42bbc14631b62504..1e97b8d9a159b43840484566cfff6c9913a60dfd 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1054,6 +1054,9 @@ 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;