Re: [PATCH net-next] tipc: Fix NULL pointer dereference in __tipc_sendstream()

From: YueHaibing <redacted>
Date: Thu, 28 May 2020 22:34:07 +0800

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 <redacted>

I spent some time reading this a few times and the Fixes: commit and
this change looks ok to me so I'm just going to apply this.

Thanks.