netdev - [PATCH 1/9] net/rds: Check address length before reading address family

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Message-Id: <1555066312-9317-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp>
Date:   Fri, 12 Apr 2019 19:51:52 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Santosh Shilimkar <santosh.shilimkar@...cle.com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        syzbot <syzbot+0049bebbf3042dbd2e8f@...kaller.appspotmail.com>,
        syzbot <syzbot+915c9f99f3dbc4bd6cd1@...kaller.appspotmail.com>
Subject: [PATCH 1/9] net/rds: Check address length before reading address family

syzbot is reporting uninitialized value at rds_connect() [1] and
rds_bind() [2]. This is because syzbot is passing ulen == 0 whereas
these functions expect that it is safe to access sockaddr->family field
in order to determine minimal address length for validation.

[1] https://syzkaller.appspot.com/bug?id=f4e61c010416c1e6f0fa3ffe247561b60a50ad71
[2] https://syzkaller.appspot.com/bug?id=a4bf9e41b7e055c3823fdcd83e8c58ca7270e38f

Reported-by: syzbot <syzbot+0049bebbf3042dbd2e8f@...kaller.appspotmail.com>
Reported-by: syzbot <syzbot+915c9f99f3dbc4bd6cd1@...kaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 net/rds/af_rds.c | 3 +++
 net/rds/bind.c   | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index d6cc97fbbbb0..2b969f99ef13 100644
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -543,6 +543,9 @@ static int rds_connect(struct socket *sock, struct sockaddr *uaddr,
 	struct rds_sock *rs = rds_sk_to_rs(sk);
 	int ret = 0;
 
+	if (addr_len < offsetofend(struct sockaddr, sa_family))
+		return -EINVAL;
+
 	lock_sock(sk);
 
 	switch (uaddr->sa_family) {
diff --git a/net/rds/bind.c b/net/rds/bind.c
index 17c9d9f0c848..0f4398e7f2a7 100644
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -173,6 +173,8 @@ int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 	/* We allow an RDS socket to be bound to either IPv4 or IPv6
 	 * address.
 	 */
+	if (addr_len < offsetofend(struct sockaddr, sa_family))
+		return -EINVAL;
 	if (uaddr->sa_family == AF_INET) {
 		struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
 
-- 
2.16.5