[PATCH 5.7 015/112] tipc: Fix NULL pointer dereference in __tipc_sendstream()

Greg Kroah-Hartman
2020-07-07T15:23:02Z

From: YueHaibing <yuehaibing@huawei.com>

[ Upstream commit 4c21daae3dbc9f8536cc18e6e53627821fa2c90c ]

tipc_sendstream() may send zero length packet, then tipc_msg_append()
do not alloc skb, skb_peek_tail() will get NULL, msg_set_ack_required
will trigger NULL pointer dereference.

Reported-by: syzbot+8eac6d030e7807c21d32@syzkaller.appspotmail.com
Fixes: 0a3e060f340d ("tipc: add test for Nagle algorithm effectiveness")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/tipc/socket.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 62fc871a8d673..f02f2abf6e3c0 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1589,8 +1589,12 @@ static int __tipc_sendstream(struct socket *sock, struct msghdr *m, size_t dlen)
tsk->pkt_cnt += skb_queue_len(txq);
} else {
skb = skb_peek_tail(txq);
- msg_set_ack_required(buf_msg(skb));
- tsk->expect_ack = true;
+ if (skb) {
+ msg_set_ack_required(buf_msg(skb));
+ tsk->expect_ack = true;
+ } else {
+ tsk->expect_ack = false;
+ }
tsk->msg_acc = 0;
tsk->pkt_cnt = 0;
}
--
2.25.1