lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 29 Jan 2012 22:49:40 -0800 From: Nandita Dukkipati <nanditad@...gle.com> To: Neal Cardwell <ncardwell@...gle.com> Cc: David Miller <davem@...emloft.net>, netdev@...r.kernel.org, ilpo.jarvinen@...sinki.fi, Yuchung Cheng <ycheng@...gle.com>, Tom Herbert <therbert@...gle.com> Subject: Re: [PATCH] tcp: fix tcp_trim_head() to adjust segment count with skb MSS On Sat, Jan 28, 2012 at 7:29 PM, Neal Cardwell <ncardwell@...gle.com> wrote: > > This commit fixes tcp_trim_head() to recalculate the number of > segments in the skb with the skb's existing MSS, so trimming the head > causes the skb segment count to be monotonically non-increasing - it > should stay the same or go down, but not increase. > > Previously tcp_trim_head() used the current MSS of the connection. But > if there was a decrease in MSS between original transmission and ACK > (e.g. due to PMTUD), this could cause tcp_trim_head() to > counter-intuitively increase the segment count when trimming bytes off > the head of an skb. This violated assumptions in tcp_tso_acked() that > tcp_trim_head() only decreases the packet count, so that packets_acked > in tcp_tso_acked() could underflow, leading tcp_clean_rtx_queue() to > pass u32 pkts_acked values as large as 0xffffffff to > ca_ops->pkts_acked(). > > As an aside, if tcp_trim_head() had really wanted the skb to reflect > the current MSS, it should have called tcp_set_skb_tso_segs() > unconditionally, since a decrease in MSS would mean that a > single-packet skb should now be sliced into multiple segments. > > Signed-off-by: Neal Cardwell <ncardwell@...gle.com> Acked-by: Nandita Dukkipati <nanditad@...gle.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists