ipv6: tcp: fix potential NULL deref in tcp_v6_send_reset()
syzbot found a crash in tcp_v6_send_reset() caused by my latest
change.
Problem is that if an skb has been queued to socket prequeue,
skb_dst(skb)->dev can not anymore point to the device.
Fortunately in this case the socket pointer is not NULL.
A similar issue has been fixed in commit
b5a346c12c70 ("tcp: fix
more NULL deref after prequeue changes"), I should have known better.
Fixes: b75582f80200 ("ipv6: tcp: enable flowlabel reflection in some RST packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>