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Message-ID: <CAK6E8=cXWVgTKY2tVOdMgAKGv4eE-6H4WVrDPw_3QfnVH9t_3Q@mail.gmail.com>
Date: Wed, 19 Jun 2019 09:57:57 -0700
From: Yuchung Cheng <ycheng@...gle.com>
To: Soheil Hassas Yeganeh <soheil@...gle.com>
Cc: Eric Dumazet <edumazet@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>,
Eric Dumazet <eric.dumazet@...il.com>,
Neal Cardwell <ncardwell@...gle.com>,
syzbot <syzkaller@...glegroups.com>
Subject: Re: [PATCH net] inet: clear num_timeout reqsk_alloc()
On Wed, Jun 19, 2019 at 9:46 AM Soheil Hassas Yeganeh <soheil@...gle.com> wrote:
>
> On Wed, Jun 19, 2019 at 12:38 PM Eric Dumazet <edumazet@...gle.com> wrote:
> >
> > KMSAN caught uninit-value in tcp_create_openreq_child() [1]
> > This is caused by a recent change, combined by the fact
> > that TCP cleared num_timeout, num_retrans and sk fields only
> > when a request socket was about to be queued.
> >
> > Under syncookie mode, a temporary request socket is used,
> > and req->num_timeout could contain garbage.
> >
> > Lets clear these three fields sooner, there is really no
> > point trying to defer this and risk other bugs.
> >
> > [1]
> >
> > BUG: KMSAN: uninit-value in tcp_create_openreq_child+0x157f/0x1cc0 net/ipv4/tcp_minisocks.c:526
> > CPU: 1 PID: 13357 Comm: syz-executor591 Not tainted 5.2.0-rc4+ #3
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> > <IRQ>
> > __dump_stack lib/dump_stack.c:77 [inline]
> > dump_stack+0x191/0x1f0 lib/dump_stack.c:113
> > kmsan_report+0x162/0x2d0 mm/kmsan/kmsan.c:611
> > __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:304
> > tcp_create_openreq_child+0x157f/0x1cc0 net/ipv4/tcp_minisocks.c:526
> > tcp_v6_syn_recv_sock+0x761/0x2d80 net/ipv6/tcp_ipv6.c:1152
> > tcp_get_cookie_sock+0x16e/0x6b0 net/ipv4/syncookies.c:209
> > cookie_v6_check+0x27e0/0x29a0 net/ipv6/syncookies.c:252
> > tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1039 [inline]
> > tcp_v6_do_rcv+0xf1c/0x1ce0 net/ipv6/tcp_ipv6.c:1344
> > tcp_v6_rcv+0x60b7/0x6a30 net/ipv6/tcp_ipv6.c:1554
> > ip6_protocol_deliver_rcu+0x1433/0x22f0 net/ipv6/ip6_input.c:397
> > ip6_input_finish net/ipv6/ip6_input.c:438 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ip6_input+0x2af/0x340 net/ipv6/ip6_input.c:447
> > dst_input include/net/dst.h:439 [inline]
> > ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ipv6_rcv+0x683/0x710 net/ipv6/ip6_input.c:272
> > __netif_receive_skb_one_core net/core/dev.c:4981 [inline]
> > __netif_receive_skb net/core/dev.c:5095 [inline]
> > process_backlog+0x721/0x1410 net/core/dev.c:5906
> > napi_poll net/core/dev.c:6329 [inline]
> > net_rx_action+0x738/0x1940 net/core/dev.c:6395
> > __do_softirq+0x4ad/0x858 kernel/softirq.c:293
> > do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1052
> > </IRQ>
> > do_softirq kernel/softirq.c:338 [inline]
> > __local_bh_enable_ip+0x199/0x1e0 kernel/softirq.c:190
> > local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
> > rcu_read_unlock_bh include/linux/rcupdate.h:682 [inline]
> > ip6_finish_output2+0x213f/0x2670 net/ipv6/ip6_output.c:117
> > ip6_finish_output+0xae4/0xbc0 net/ipv6/ip6_output.c:150
> > NF_HOOK_COND include/linux/netfilter.h:294 [inline]
> > ip6_output+0x5d3/0x720 net/ipv6/ip6_output.c:167
> > dst_output include/net/dst.h:433 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ip6_xmit+0x1f53/0x2650 net/ipv6/ip6_output.c:271
> > inet6_csk_xmit+0x3df/0x4f0 net/ipv6/inet6_connection_sock.c:135
> > __tcp_transmit_skb+0x4076/0x5b40 net/ipv4/tcp_output.c:1156
> > tcp_transmit_skb net/ipv4/tcp_output.c:1172 [inline]
> > tcp_write_xmit+0x39a9/0xa730 net/ipv4/tcp_output.c:2397
> > __tcp_push_pending_frames+0x124/0x4e0 net/ipv4/tcp_output.c:2573
> > tcp_send_fin+0xd43/0x1540 net/ipv4/tcp_output.c:3118
> > tcp_close+0x16ba/0x1860 net/ipv4/tcp.c:2403
> > inet_release+0x1f7/0x270 net/ipv4/af_inet.c:427
> > inet6_release+0xaf/0x100 net/ipv6/af_inet6.c:470
> > __sock_release net/socket.c:601 [inline]
> > sock_close+0x156/0x490 net/socket.c:1273
> > __fput+0x4c9/0xba0 fs/file_table.c:280
> > ____fput+0x37/0x40 fs/file_table.c:313
> > task_work_run+0x22e/0x2a0 kernel/task_work.c:113
> > tracehook_notify_resume include/linux/tracehook.h:185 [inline]
> > exit_to_usermode_loop arch/x86/entry/common.c:168 [inline]
> > prepare_exit_to_usermode+0x39d/0x4d0 arch/x86/entry/common.c:199
> > syscall_return_slowpath+0x90/0x5c0 arch/x86/entry/common.c:279
> > do_syscall_64+0xe2/0xf0 arch/x86/entry/common.c:305
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > RIP: 0033:0x401d50
> > Code: 01 f0 ff ff 0f 83 40 0d 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d dd 8d 2d 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 14 0d 00 00 c3 48 83 ec 08 e8 7a 02 00 00
> > RSP: 002b:00007fff1cf58cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
> > RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000401d50
> > RDX: 000000000000001c RSI: 0000000000000000 RDI: 0000000000000003
> > RBP: 00000000004a9050 R08: 0000000020000040 R09: 000000000000001c
> > R10: 0000000020004004 R11: 0000000000000246 R12: 0000000000402ef0
> > R13: 0000000000402f80 R14: 0000000000000000 R15: 0000000000000000
> >
> > Uninit was created at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:201 [inline]
> > kmsan_internal_poison_shadow+0x53/0xa0 mm/kmsan/kmsan.c:160
> > kmsan_kmalloc+0xa4/0x130 mm/kmsan/kmsan_hooks.c:177
> > kmem_cache_alloc+0x534/0xb00 mm/slub.c:2781
> > reqsk_alloc include/net/request_sock.h:84 [inline]
> > inet_reqsk_alloc+0xa8/0x600 net/ipv4/tcp_input.c:6384
> > cookie_v6_check+0xadb/0x29a0 net/ipv6/syncookies.c:173
> > tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1039 [inline]
> > tcp_v6_do_rcv+0xf1c/0x1ce0 net/ipv6/tcp_ipv6.c:1344
> > tcp_v6_rcv+0x60b7/0x6a30 net/ipv6/tcp_ipv6.c:1554
> > ip6_protocol_deliver_rcu+0x1433/0x22f0 net/ipv6/ip6_input.c:397
> > ip6_input_finish net/ipv6/ip6_input.c:438 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ip6_input+0x2af/0x340 net/ipv6/ip6_input.c:447
> > dst_input include/net/dst.h:439 [inline]
> > ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ipv6_rcv+0x683/0x710 net/ipv6/ip6_input.c:272
> > __netif_receive_skb_one_core net/core/dev.c:4981 [inline]
> > __netif_receive_skb net/core/dev.c:5095 [inline]
> > process_backlog+0x721/0x1410 net/core/dev.c:5906
> > napi_poll net/core/dev.c:6329 [inline]
> > net_rx_action+0x738/0x1940 net/core/dev.c:6395
> > __do_softirq+0x4ad/0x858 kernel/softirq.c:293
> > do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1052
> > do_softirq kernel/softirq.c:338 [inline]
> > __local_bh_enable_ip+0x199/0x1e0 kernel/softirq.c:190
> > local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
> > rcu_read_unlock_bh include/linux/rcupdate.h:682 [inline]
> > ip6_finish_output2+0x213f/0x2670 net/ipv6/ip6_output.c:117
> > ip6_finish_output+0xae4/0xbc0 net/ipv6/ip6_output.c:150
> > NF_HOOK_COND include/linux/netfilter.h:294 [inline]
> > ip6_output+0x5d3/0x720 net/ipv6/ip6_output.c:167
> > dst_output include/net/dst.h:433 [inline]
> > NF_HOOK include/linux/netfilter.h:305 [inline]
> > ip6_xmit+0x1f53/0x2650 net/ipv6/ip6_output.c:271
> > inet6_csk_xmit+0x3df/0x4f0 net/ipv6/inet6_connection_sock.c:135
> > __tcp_transmit_skb+0x4076/0x5b40 net/ipv4/tcp_output.c:1156
> > tcp_transmit_skb net/ipv4/tcp_output.c:1172 [inline]
> > tcp_write_xmit+0x39a9/0xa730 net/ipv4/tcp_output.c:2397
> > __tcp_push_pending_frames+0x124/0x4e0 net/ipv4/tcp_output.c:2573
> > tcp_send_fin+0xd43/0x1540 net/ipv4/tcp_output.c:3118
> > tcp_close+0x16ba/0x1860 net/ipv4/tcp.c:2403
> > inet_release+0x1f7/0x270 net/ipv4/af_inet.c:427
> > inet6_release+0xaf/0x100 net/ipv6/af_inet6.c:470
> > __sock_release net/socket.c:601 [inline]
> > sock_close+0x156/0x490 net/socket.c:1273
> > __fput+0x4c9/0xba0 fs/file_table.c:280
> > ____fput+0x37/0x40 fs/file_table.c:313
> > task_work_run+0x22e/0x2a0 kernel/task_work.c:113
> > tracehook_notify_resume include/linux/tracehook.h:185 [inline]
> > exit_to_usermode_loop arch/x86/entry/common.c:168 [inline]
> > prepare_exit_to_usermode+0x39d/0x4d0 arch/x86/entry/common.c:199
> > syscall_return_slowpath+0x90/0x5c0 arch/x86/entry/common.c:279
> > do_syscall_64+0xe2/0xf0 arch/x86/entry/common.c:305
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Fixes: 336c39a03151 ("tcp: undo init congestion window on false SYNACK timeout")
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> > Cc: Yuchung Cheng <ycheng@...gle.com>
> > Cc: Neal Cardwell <ncardwell@...gle.com>
> > Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
> > Reported-by: syzbot <syzkaller@...glegroups.com>
>
> Acked-by: Soheil Hassas Yeganeh <soheil@...gle.com>
>
> Thank you for the fix!
Acked-by: Yuchung Cheng <ycheng@...gle.com>
Thanks for fixing it!
>
> > ---
> > include/net/request_sock.h | 3 +++
> > net/ipv4/inet_connection_sock.c | 4 ----
> > net/ipv4/tcp_fastopen.c | 4 ----
> > 3 files changed, 3 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/net/request_sock.h b/include/net/request_sock.h
> > index b3ea21f2732ef509d47bfcecc38f78d9178a3d5c..fd178d58fa84e7ae7abdeff5be2ba7b1ec790889 100644
> > --- a/include/net/request_sock.h
> > +++ b/include/net/request_sock.h
> > @@ -97,6 +97,9 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
> > sk_node_init(&req_to_sk(req)->sk_node);
> > sk_tx_queue_clear(req_to_sk(req));
> > req->saved_syn = NULL;
> > + req->num_timeout = 0;
> > + req->num_retrans = 0;
> > + req->sk = NULL;
> > refcount_set(&req->rsk_refcnt, 0);
> >
> > return req;
> > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> > index 13ec7c3a9c49f02ed359f3f941c8ff70f4699695..7fd6db3fe3664b02fa0279a6aef08144588de6e4 100644
> > --- a/net/ipv4/inet_connection_sock.c
> > +++ b/net/ipv4/inet_connection_sock.c
> > @@ -752,10 +752,6 @@ static void reqsk_timer_handler(struct timer_list *t)
> > static void reqsk_queue_hash_req(struct request_sock *req,
> > unsigned long timeout)
> > {
> > - req->num_retrans = 0;
> > - req->num_timeout = 0;
> > - req->sk = NULL;
> > -
> > timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
> > mod_timer(&req->rsk_timer, jiffies + timeout);
> >
> > diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
> > index 018a484773551f8e67fe20be97b04f6d02104a56..f5a45e1e118224966e336725de71d3636b207892 100644
> > --- a/net/ipv4/tcp_fastopen.c
> > +++ b/net/ipv4/tcp_fastopen.c
> > @@ -221,10 +221,6 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk,
> > struct sock *child;
> > bool own_req;
> >
> > - req->num_retrans = 0;
> > - req->num_timeout = 0;
> > - req->sk = NULL;
> > -
> > child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
> > NULL, &own_req);
> > if (!child)
> > --
> > 2.22.0.410.gd8fdbe21b5-goog
> >
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