WARNING: SOFTIRQ-READ-safe -> SOFTIRQ-READ-unsafe lock order detected

From: syzbot
Date: Wed Sep 16 2020 - 05:02:42 EST

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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@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
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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