linux-kernel - [PATCH] netlink: make sure nladdr has correct size in netlink

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Message-Id: <20180323124902.41625-1-glider@google.com>
Date:   Fri, 23 Mar 2018 13:49:02 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     dvyukov@...gle.com, edumazet@...gle.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] 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@...gle.com>
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