From: Eric Dumazet <eric.dumazet@gmail.com>
To: Thomas Graf <tgraf@suug.ch>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [PATCH] net: Convert skb->csum_(start|offset) integrity BUG_ON() to WARN_ON() & drop
Date: Thu, 14 Feb 2013 08:22:23 -0800 [thread overview]
Message-ID: <1360858943.6884.47.camel@edumazet-glaptop> (raw)
In-Reply-To: <20130214101853.GC21829@casper.infradead.org>
On Thu, 2013-02-14 at 10:18 +0000, Thomas Graf wrote:
> Maybe it's my general dislike of BUG_ON() in the processing
> path, especially if the bug condition can be influenced remotely.
> It looks absolutely doable to trigger the previously mentioned
> partial acking & collapsing on purpose by a malicious receiver
> even with an MTU of 1500. I believe we should avoid total DoS
> in future similar situations that we don't think of yet.
It seems not possible to avoid bugs, being a BUG_ON() or a out of bound
memory access or whatever. We must fix them eventually.
In this case, it seems we must limit payload to
65535 - MAX_TCP_HEADER
It would make tcp_xmit_size_goal() a bit shorter.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2c7e596..2f6c8e5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -793,10 +793,7 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
xmit_size_goal = mss_now;
if (large_allowed && sk_can_gso(sk)) {
- xmit_size_goal = ((sk->sk_gso_max_size - 1) -
- inet_csk(sk)->icsk_af_ops->net_header_len -
- inet_csk(sk)->icsk_ext_hdr_len -
- tp->tcp_header_len);
+ xmit_size_goal = sk->sk_gso_max_size - 1 - MAX_TCP_HEADER;
/* TSQ : try to have two TSO segments in flight */
xmit_size_goal = min_t(u32, xmit_size_goal,
next prev parent reply other threads:[~2013-02-14 16:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 23:40 [PATCH] net: Convert skb->csum_(start|offset) integrity BUG_ON() to WARN_ON() & drop Thomas Graf
2013-02-13 23:48 ` Thomas Graf
2013-02-14 0:37 ` David Miller
2013-02-14 10:18 ` Thomas Graf
2013-02-14 16:22 ` Eric Dumazet [this message]
2013-02-14 18:50 ` Thomas Graf
2013-02-14 19:21 ` Eric Dumazet
2013-02-14 18:00 ` David Miller
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