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Message-ID: <0000000000007815da05af6a86f3@google.com>
Date:   Wed, 16 Sep 2020 02:02:20 -0700
From:   syzbot <syzbot+9b6f24d0e72fbed27319@...kaller.appspotmail.com>
To:     davem@...emloft.net, herbert@...dor.apana.org.au, kuba@...nel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        steffen.klassert@...unet.com, syzkaller-bugs@...glegroups.com
Subject: WARNING: SOFTIRQ-READ-safe -> SOFTIRQ-READ-unsafe lock order detected

Hello,

syzbot found the following issue on:

HEAD commit:    6b02addb Add linux-next specific files for 20200915
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1148b901900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7086d0e9e44d4a14
dashboard link: https://syzkaller.appspot.com/bug?extid=9b6f24d0e72fbed27319
compiler:       gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b6f24d0e72fbed27319@...kaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-READ-safe -> SOFTIRQ-READ-unsafe lock order detected
5.9.0-rc5-next-20200915-syzkaller #0 Not tainted
-----------------------------------------------------
kworker/0:17/14303 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffff88809ff56128 (&s->seqcount#11){+.+.}-{0:0}, at: xfrm_policy_inexact_insert+0xb9/0xbb0 net/xfrm/xfrm_policy.c:1189

and this task is already holding:
ffffffff8ae7a108 (&s->seqcount#12){+..-}-{0:0}, at: process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
which would create a new lock dependency:
 (&s->seqcount#12){+..-}-{0:0} -> (&s->seqcount#11){+.+.}-{0:0}

but this new dependency connects a SOFTIRQ-READ-irq-safe lock:
 (&s->seqcount#12){+..-}-{0:0}

... which became SOFTIRQ-READ-irq-safe at:
  lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
  seqcount_lockdep_reader_access+0x139/0x1a0 include/linux/seqlock.h:103
  xfrm_policy_lookup_bytype+0x183/0xa40 net/xfrm/xfrm_policy.c:2088
  xfrm_policy_lookup net/xfrm/xfrm_policy.c:2139 [inline]
  __xfrm_policy_check+0xb53/0x2650 net/xfrm/xfrm_policy.c:3572
  __xfrm_policy_check2 include/net/xfrm.h:1097 [inline]
  xfrm_policy_check include/net/xfrm.h:1106 [inline]
  xfrm6_policy_check include/net/xfrm.h:1116 [inline]
  udpv6_queue_rcv_one_skb+0x570/0x15c0 net/ipv6/udp.c:660
  udpv6_queue_rcv_skb net/ipv6/udp.c:744 [inline]
  udp6_unicast_rcv_skb+0x259/0x490 net/ipv6/udp.c:886
  __udp6_lib_rcv+0xb35/0x2750 net/ipv6/udp.c:970
  ip6_protocol_deliver_rcu+0x2e8/0x1660 net/ipv6/ip6_input.c:433
  ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
  NF_HOOK include/linux/netfilter.h:301 [inline]
  NF_HOOK include/linux/netfilter.h:295 [inline]
  ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
  dst_input include/net/dst.h:449 [inline]
  ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
  NF_HOOK include/linux/netfilter.h:301 [inline]
  NF_HOOK include/linux/netfilter.h:295 [inline]
  ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
  __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
  __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
  process_backlog+0x2e1/0x8e0 net/core/dev.c:6286
  napi_poll net/core/dev.c:6730 [inline]
  net_rx_action+0x572/0x1300 net/core/dev.c:6800
  __do_softirq+0x202/0xa42 kernel/softirq.c:298
  asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786
  __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
  run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
  do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
  do_softirq kernel/softirq.c:343 [inline]
  do_softirq+0x154/0x1b0 kernel/softirq.c:330
  __local_bh_enable_ip+0x196/0x1f0 kernel/softirq.c:195
  wg_socket_send_skb_to_peer+0x14b/0x220 drivers/net/wireguard/socket.c:183
  wg_packet_create_data_done drivers/net/wireguard/send.c:252 [inline]
  wg_packet_tx_worker+0x2f9/0x980 drivers/net/wireguard/send.c:280
  process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
  worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
  kthread+0x3af/0x4a0 kernel/kthread.c:292
  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

to a SOFTIRQ-READ-irq-unsafe lock:
 (&s->seqcount#11){+.+.}-{0:0}

... which became SOFTIRQ-READ-irq-unsafe at:
...
  lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
  write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
  write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
  write_seqlock include/linux/seqlock.h:883 [inline]
  xfrm_set_spdinfo+0x302/0x660 net/xfrm/xfrm_user.c:1185
  xfrm_user_rcv_msg+0x414/0x700 net/xfrm/xfrm_user.c:2684
  netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
  xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2692
  netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
  sock_sendmsg_nosec net/socket.c:651 [inline]
  sock_sendmsg+0xcf/0x120 net/socket.c:671
  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2362
  ___sys_sendmsg+0xf3/0x170 net/socket.c:2416
  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2449
  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&s->seqcount#11);
                               local_irq_disable();
                               lock(&s->seqcount#12);
                               lock(&s->seqcount#11);
  <Interrupt>
    lock(&s->seqcount#12);

 *** DEADLOCK ***

5 locks held by kworker/0:17/14303:
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x821/0x15a0 kernel/workqueue.c:2240
 #1: ffffc90008a3fda8 ((work_completion)(&net->xfrm.policy_hthresh.work)){+.+.}-{0:0}, at: process_one_work+0x854/0x15a0 kernel/workqueue.c:2244
 #2: ffffffff8abc5f08 (hash_resize_mutex){+.+.}-{3:3}, at: xfrm_hash_rebuild+0x54/0x1110 net/xfrm/xfrm_policy.c:1225
 #3: ffff8880a6b45a18 (&net->xfrm.xfrm_policy_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline]
 #3: ffff8880a6b45a18 (&net->xfrm.xfrm_policy_lock){+...}-{2:2}, at: xfrm_hash_rebuild+0x1e4/0x1110 net/xfrm/xfrm_policy.c:1237
 #4: ffffffff8ae7a108 (&s->seqcount#12){+..-}-{0:0}, at: process_one_work+0x933/0x15a0 kernel/workqueue.c:2269

the dependencies between SOFTIRQ-READ-irq-safe lock and the holding lock:
-> (&s->seqcount#12){+..-}-{0:0} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
                    write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
                    write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
                    xfrm_hash_rebuild+0x261/0x1110 net/xfrm/xfrm_policy.c:1238
                    process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
                    worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
                    kthread+0x3af/0x4a0 kernel/kthread.c:292
                    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
   IN-SOFTIRQ-R at:
                    lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
                    seqcount_lockdep_reader_access+0x139/0x1a0 include/linux/seqlock.h:103
                    xfrm_policy_lookup_bytype+0x183/0xa40 net/xfrm/xfrm_policy.c:2088
                    xfrm_policy_lookup net/xfrm/xfrm_policy.c:2139 [inline]
                    __xfrm_policy_check+0xb53/0x2650 net/xfrm/xfrm_policy.c:3572
                    __xfrm_policy_check2 include/net/xfrm.h:1097 [inline]
                    xfrm_policy_check include/net/xfrm.h:1106 [inline]
                    xfrm6_policy_check include/net/xfrm.h:1116 [inline]
                    udpv6_queue_rcv_one_skb+0x570/0x15c0 net/ipv6/udp.c:660
                    udpv6_queue_rcv_skb net/ipv6/udp.c:744 [inline]
                    udp6_unicast_rcv_skb+0x259/0x490 net/ipv6/udp.c:886
                    __udp6_lib_rcv+0xb35/0x2750 net/ipv6/udp.c:970
                    ip6_protocol_deliver_rcu+0x2e8/0x1660 net/ipv6/ip6_input.c:433
                    ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
                    NF_HOOK include/linux/netfilter.h:301 [inline]
                    NF_HOOK include/linux/netfilter.h:295 [inline]
                    ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
                    dst_input include/net/dst.h:449 [inline]
                    ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
                    NF_HOOK include/linux/netfilter.h:301 [inline]
                    NF_HOOK include/linux/netfilter.h:295 [inline]
                    ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
                    __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
                    __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
                    process_backlog+0x2e1/0x8e0 net/core/dev.c:6286
                    napi_poll net/core/dev.c:6730 [inline]
                    net_rx_action+0x572/0x1300 net/core/dev.c:6800
                    __do_softirq+0x202/0xa42 kernel/softirq.c:298
                    asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786
                    __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
                    run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
                    do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
                    do_softirq kernel/softirq.c:343 [inline]
                    do_softirq+0x154/0x1b0 kernel/softirq.c:330
                    __local_bh_enable_ip+0x196/0x1f0 kernel/softirq.c:195
                    wg_socket_send_skb_to_peer+0x14b/0x220 drivers/net/wireguard/socket.c:183
                    wg_packet_create_data_done drivers/net/wireguard/send.c:252 [inline]
                    wg_packet_tx_worker+0x2f9/0x980 drivers/net/wireguard/send.c:280
                    process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
                    worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
                    kthread+0x3af/0x4a0 kernel/kthread.c:292
                    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
   INITIAL USE at:
                   lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
                   seqcount_lockdep_reader_access+0x139/0x1a0 include/linux/seqlock.h:103
                   xfrm_policy_lookup_bytype+0x183/0xa40 net/xfrm/xfrm_policy.c:2088
                   xfrm_policy_lookup net/xfrm/xfrm_policy.c:2139 [inline]
                   __xfrm_policy_check+0xb53/0x2650 net/xfrm/xfrm_policy.c:3572
                   __xfrm_policy_check2 include/net/xfrm.h:1097 [inline]
                   xfrm_policy_check include/net/xfrm.h:1106 [inline]
                   xfrm6_policy_check include/net/xfrm.h:1116 [inline]
                   udpv6_queue_rcv_one_skb+0x570/0x15c0 net/ipv6/udp.c:660
                   udpv6_queue_rcv_skb net/ipv6/udp.c:744 [inline]
                   udp6_unicast_rcv_skb+0x259/0x490 net/ipv6/udp.c:886
                   __udp6_lib_rcv+0xb35/0x2750 net/ipv6/udp.c:970
                   ip6_protocol_deliver_rcu+0x2e8/0x1660 net/ipv6/ip6_input.c:433
                   ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
                   NF_HOOK include/linux/netfilter.h:301 [inline]
                   NF_HOOK include/linux/netfilter.h:295 [inline]
                   ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
                   dst_input include/net/dst.h:449 [inline]
                   ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
                   NF_HOOK include/linux/netfilter.h:301 [inline]
                   NF_HOOK include/linux/netfilter.h:295 [inline]
                   ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
                   __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
                   __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
                   process_backlog+0x2e1/0x8e0 net/core/dev.c:6286
                   napi_poll net/core/dev.c:6730 [inline]
                   net_rx_action+0x572/0x1300 net/core/dev.c:6800
                   __do_softirq+0x202/0xa42 kernel/softirq.c:298
                   asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786
                   __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
                   run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
                   do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
                   do_softirq kernel/softirq.c:343 [inline]
                   do_softirq+0x154/0x1b0 kernel/softirq.c:330
                   __local_bh_enable_ip+0x196/0x1f0 kernel/softirq.c:195
                   wg_socket_send_skb_to_peer+0x14b/0x220 drivers/net/wireguard/socket.c:183
                   wg_packet_create_data_done drivers/net/wireguard/send.c:252 [inline]
                   wg_packet_tx_worker+0x2f9/0x980 drivers/net/wireguard/send.c:280
                   process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
                   worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
                   kthread+0x3af/0x4a0 kernel/kthread.c:292
                   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
   (null) at:
general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 PID: 14303 Comm: kworker/0:17 Not tainted 5.9.0-rc5-next-20200915-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events xfrm_hash_rebuild
RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline]
RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline]
RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263
Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 b1 21 d9 f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
RSP: 0018:ffffc90008a3f6e8 EFLAGS: 00010002
RAX: 000000000000000c RBX: ffffc90008a3f840 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff815c26a7 RDI: 0000000000000020
RBP: ffffc90008a3f840 R08: 0000000000000004 R09: ffff8880ae620f8b
R10: 0000000000000000 R11: 6c6c756e28202020 R12: dffffc0000000000
R13: ffffffff8ca46f40 R14: 0000000000000009 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000744138 CR3: 000000004e370000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 print_bad_irq_dependency kernel/locking/lockdep.c:2395 [inline]
 check_irq_usage.cold+0x42d/0x5b0 kernel/locking/lockdep.c:2634
 check_prev_add kernel/locking/lockdep.c:2823 [inline]
 check_prevs_add kernel/locking/lockdep.c:2944 [inline]
 validate_chain kernel/locking/lockdep.c:3562 [inline]
 __lock_acquire+0x2800/0x55d0 kernel/locking/lockdep.c:4796
 lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
 write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
 write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
 xfrm_policy_inexact_alloc_chain.isra.0+0x3c6/0x9b0 net/xfrm/xfrm_policy.c:1145
 xfrm_policy_inexact_insert+0xb9/0xbb0 net/xfrm/xfrm_policy.c:1189
 xfrm_hash_rebuild+0xdca/0x1110 net/xfrm/xfrm_policy.c:1327
 process_one_work+0x933/0x15a0 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3af/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
---[ end trace fb36ab3ee2fc8525 ]---
RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline]
RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline]
RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263
Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 b1 21 d9 f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
RSP: 0018:ffffc90008a3f6e8 EFLAGS: 00010002
RAX: 000000000000000c RBX: ffffc90008a3f840 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff815c26a7 RDI: 0000000000000020
RBP: ffffc90008a3f840 R08: 0000000000000004 R09: ffff8880ae620f8b
R10: 0000000000000000 R11: 6c6c756e28202020 R12: dffffc0000000000
R13: ffffffff8ca46f40 R14: 0000000000000009 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000744138 CR3: 000000004e370000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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