Hi Wang Cong,
With this patch , the system was crashed when setsockopt.
The call trace as below:
crash> bt
PID: 3069 TASK: ffff8800afcc0000 CPU: 0 COMMAND: "trinity-main"
#0 [ffff8801bec03ce0] machine_kexec at ffffffff8105354b
#1 [ffff8801bec03d40] crash_kexec at ffffffff810f7e82
#2 [ffff8801bec03e10] panic at ffffffff81650058
#3 [ffff8801bec03e90] watchdog_timer_fn at ffffffff81122533
#4 [ffff8801bec03ec8] __hrtimer_run_queues at ffffffff810abeb2
#5 [ffff8801bec03f20] hrtimer_interrupt at ffffffff810ac450
#6 [ffff8801bec03f70] local_apic_timer_interrupt at ffffffff8104a457
#7 [ffff8801bec03f88] smp_apic_timer_interrupt at ffffffff8166aed0
#8 [ffff8801bec03fb0] apic_timer_interrupt at ffffffff8166931d
--- <IRQ stack> ---
#9 [ffff8801b301fcb8] apic_timer_interrupt at ffffffff8166931d
[exception RIP: lock_timer_base+77]
RIP: ffffffff8108dced RSP: ffff8801b301fd60 RFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8800afcc0000 RCX: 0000000000000001
RDX: ffff8800afcc0000 RSI: ffff8801b301fd90 RDI: ffff8800b0d853c8
RBP: ffff8801b301fd80 R8: ffff8800afcc0000 R9: ffffea0002680000
R10: 000000000000003c R11: ffff8801b301fb2e R12: ffff8800afcc0000
R13: ffff8800afcc0000 R14: 0000000000000000 R15: ffffffff83d1a340
ORIG_RAX: ffffffffffffff10 CS: 0010 SS: 0018
#10 [ffff8801b301fd88] try_to_del_timer_sync at ffffffff8108f19f
#11 [ffff8801b301fdb8] del_timer_sync at ffffffff8108f252
#12 [ffff8801b301fdd0] packet_set_ring at ffffffff81635e60
#13 [ffff8801b301fe98] packet_setsockopt at ffffffff81636760
#14 [ffff8801b301ff38] sys_setsockopt at ffffffff81531860
#15 [ffff8801b301ff80] tracesys at ffffffff816687ed (via system_call)
RIP: 00007fcc78b03e3a RSP: 00007fff16f246b8 RFLAGS: 00000202
RAX: ffffffffffffffda RBX: ffffffff816687ed RCX: ffffffffffffffff
RDX: 0000000000000005 RSI: 0000000000000107 RDI: 0000000000000180
RBP: 0000000000000180 R8: 000000000000001c R9: 00007fcc78dc7160
R10: 0000000001fd6ba0 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000011 R14: 0000000001fd6b60 R15: 0000000001fd6b70
ORIG_RAX: 0000000000000036 CS: 0033 SS: 002b
Best Regards,
liujian
> -----Original Message-----
> From: Cong Wang [mailto:xiyou.wangc...@gmail.com]
> Sent: Sunday, July 23, 2017 1:59 PM
> To: Dingtianhong
> Cc: liujian (CE); Willem de Bruijn; Dave Jones; alexander.le...@verizon.com;
> da...@davemloft.net; eduma...@google.com; will...@google.com;
> dan...@iogearbox.net; net...@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: af_packet: use after free in prb_retire_rx_blk_timer_expired
>
> On Sat, Jul 22, 2017 at 8:40 PM, Ding Tianhong <dingtianh...@huawei.com>
> wrote:
> > Hi, Cong:
> >
> > Thanks for your quirk solution, but I still has some doubts about it,
> > it looks like fix the problem in the
> > packet_setsockopt->packet_set_ring processing, but when in
> > packet_release processing, it may could not release the real pg_vec
> > for the TPACKET_V3 ring, and then cause the mem leak, maybe I miss
> > something here, nice to hear from your feedback. :)
>
> Yes you miss that packet_release() has memset()'s so we won't hit that path.
> :)
>
> However, I missed the swap() in this messy function, actually I believe the
> bug
> is that we modify tpacket_kbdq_core inside rx_ring in non-closing case without
> actually stopping its timer. I feel more confident with the following patch:
>
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index
> 008bb34ee324..267b181fef15 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -4263,6 +4263,7 @@ static int packet_set_ring(struct sock *sk, union
> tpacket_req_u *req_u,
> case TPACKET_V3:
> /* Block transmit is not supported yet */
> if (!tx_ring) {
> + prb_shutdown_retire_blk_timer(po,
> + rb_queue);
> init_prb_bdqc(po, rb, pg_vec, req_u);
> } else {
> struct tpacket_req3 *req3 =
> &req_u->req3;
