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

From: Alexander Potapenko
Date: Fri Mar 23 2018 - 08:49:57 EST


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")
---
v2: fixed a typo spotted by Eric Dumazet
---
net/netlink/af_netlink.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 07e8478068f0..70c455341243 100644
--- 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;
--
2.17.0.rc0.231.g781580f067-goog