On Fri, 2014-10-31 at 09:24 -0700, Alexei Starovoitov wrote: > cc-ing netdev > > On Fri, Oct 31, 2014 at 7:50 AM, Chen Weilong <chenweil...@huawei.com> wrote: > > From: Weilong Chen <chenweil...@huawei.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. > > ouch. Is it remote exploitable?
Seems to be SYN crossing. Quite hard, but possible. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
