[PATCH 3.2 145/153] netlink: make sure nladdr has correct size in netlink_connect()

[Ben Hutchings]

3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Alexander Potapenko <glider@xxxxxxxxxx>

commit 7880287981b60a6808f39f297bb66936e8bdf57a upstream.

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@xxxxxxxxxx>
Fixes: 1da177e4c3f41524 ("Linux-2.6.12-rc2")
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/netlink/af_netlink.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -706,6 +706,9 @@ static int netlink_connect(struct socket
 	if (addr->sa_family != AF_NETLINK)
 		return -EINVAL;
 
+	if (alen < sizeof(struct sockaddr_nl))
+		return -EINVAL;
+
 	/* Only superuser is allowed to send multicasts */
 	if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND))
 		return -EPERM;