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: Fri, 31 Oct 2014 22:50:47 +0800 From: Chen Weilong <chenweilong@...wei.com> To: <davem@...emloft.net>, <kuznet@....inr.ac.ru>, <jmorris@...ei.org>, <yoshfuji@...ux-ipv6.org>, <kaber@...sh.net> CC: <linux-kernel@...r.kernel.org> Subject: [PATCH] ipv4: avoid divide 0 error in tcp_incr_quickack From: Weilong Chen <chenweilong@...wei.com> We got a problem like this: [ffff8801c1a05570] machine_kexec at ffffffff81025039 [ffff8801c1a055d0] crash_kexec at ffffffff8109b253 [ffff8801c1a056a0] oops_end at ffffffff81442aed [ffff8801c1a056d0] die at ffffffff81005603 [ffff8801c1a05700] do_trap at ffffffff81442448 [ffff8801c1a05760] do_divide_error at ffffffff81002c10 [ffff8801c1a05888] tcp_send_dupack at ffffffff81385e44 [ffff8801c1a058c8] tcp_validate_incoming at ffffffff813886b5 [ffff8801c1a05908] tcp_rcv_state_process at ffffffff8138d0b7 [ffff8801c1a05958] tcp_child_process at ffffffff81397255 [ffff8801c1a05988] tcp_v4_do_rcv at ffffffff81395a70 [ffff8801c1a059d8] tcp_v4_rcv at ffffffff81396fc8 [ffff8801c1a05a48] ip_local_deliver_finish at ffffffff813746e9 [ffff8801c1a05a78] ip_local_deliver at ffffffff81374a20 [ffff8801c1a05aa8] ip_rcv_finish at ffffffff81374389 [ffff8801c1a05ad8] ip_rcv at ffffffff81374c78 There was a wrong ack packet coming during TCP handshake. The socket's state was TCP_SYN_RECV, its rcv_mss was not initialize yet. So tcp_send_dupack -> tcp_enter_quickack_mode got a divide 0 error. This patch add a state check before tcp_enter_quickack_mode. Signed-off-by: Weilong Chen <chenweilong@...wei.com> --- net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 4e4617e..9eb56dc 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3986,7 +3986,8 @@ static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb) if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq && before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) { NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOST); - tcp_enter_quickack_mode(sk); + if (sk->sk_state != TCP_SYN_RECV) + tcp_enter_quickack_mode(sk); if (tcp_is_sack(tp) && sysctl_tcp_dsack) { u32 end_seq = TCP_SKB_CB(skb)->end_seq; -- 1.7.12 -- 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/
Powered by blists - more mailing lists