diff options
| author | Eric Dumazet <edumazet@google.com> | 2020-03-19 12:49:55 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-03-19 21:35:55 -0700 |
| commit | b738a185beaab8728943acdb3e67371b8a88185e (patch) | |
| tree | 83df18e962f606ec1966eb84b344e59f8f03d93a /net | |
| parent | f1f20a8666c55cb534b8f3fc1130eebf01a06155 (diff) | |
tcp: ensure skb->dev is NULL before leaving TCP stack
skb->rbnode is sharing three skb fields : next, prev, dev
When a packet is sent, TCP keeps the original skb (master)
in a rtx queue, which was converted to rbtree a while back.
__tcp_transmit_skb() is responsible to clone the master skb,
and add the TCP header to the clone before sending it
to network layer.
skb_clone() already clears skb->next and skb->prev, but copies
the master oskb->dev into the clone.
We need to clear skb->dev, otherwise lower layers could interpret
the value as a pointer to a netdev.
This old bug surfaced recently when commit 28f8bfd1ac94
("netfilter: Support iif matches in POSTROUTING") was merged.
Before this netfilter commit, skb->dev value was ignored and
changed before reaching dev_queue_xmit()
Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue")
Fixes: 28f8bfd1ac94 ("netfilter: Support iif matches in POSTROUTING")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Martin Zaharinov <micron10@gmail.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_output.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 306e25d743e8..e8cf8fde3d37 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1109,6 +1109,10 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, if (unlikely(!skb)) return -ENOBUFS; + /* retransmit skbs might have a non zero value in skb->dev + * because skb->dev is aliased with skb->rbnode.rb_left + */ + skb->dev = NULL; } inet = inet_sk(sk); |