From 4c21daae3dbc9f8536cc18e6e53627821fa2c90c Mon Sep 17 00:00:00 2001
From: YueHaibing <yuehaibing@huawei.com>
Date: Thu, 28 May 2020 22:34:07 +0800
Subject: [PATCH] tipc: Fix NULL pointer dereference in __tipc_sendstream()
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>
---
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 3734cdbedc9cc..26123f4177fd2 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1588,8 +1588,12 @@ 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;
}
--
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