linux-kernel - [ 52/61] tcp: detect SYN/data drop when F-RTO is disabled

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 12 Feb 2013 12:35:12 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Yuchung Cheng <ycheng@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 52/61] tcp: detect SYN/data drop when F-RTO is disabled

3.7-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Yuchung Cheng <ycheng@...gle.com>

[ Upstream commit 66555e92fb7a619188c02cceae4bbc414f15f96d ]

On receiving the SYN-ACK, Fast Open checks icsk_retransmit for SYN
retransmission to detect SYN/data drops. But if F-RTO is disabled,
icsk_retransmit is reset at step D of tcp_fastretrans_alert() (
under tcp_ack()) before tcp_rcv_fastopen_synack(). The fix is to use
total_retrans instead which accounts for SYN retransmission regardless
the use of F-RTO.

Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_input.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5639,8 +5639,7 @@ static bool tcp_rcv_fastopen_synack(stru
 	 * the remote receives only the retransmitted (regular) SYNs: either
 	 * the original SYN-data or the corresponding SYN-ACK is lost.
 	 */
-	syn_drop = (cookie->len <= 0 && data &&
-		    inet_csk(sk)->icsk_retransmits);
+	syn_drop = (cookie->len <= 0 && data && tp->total_retrans);
 
 	tcp_fastopen_cache_set(sk, mss, cookie, syn_drop);
 


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/