[syzbot] possible deadlock in j1939_sk_errqueue

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7cd8b1542a7b ptp_pch: Load module automatically if ID matc..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=12ebf7df300000
kernel config: https://syzkaller.appspot.com/x/.config?x=9290a409049988d4
dashboard link: https://syzkaller.appspot.com/bug?extid=ee1cd780f69483a8616b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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+ee1cd7...@syzkaller.appspotmail.com

vcan0: j1939_tp_rxtimer: 0xffff8881480fd400: rx timeout, send abort
======================================================
WARNING: possible circular locking dependency detected
5.15.0-rc3-syzkaller #0 Not tainted
------------------------------------------------------
kworker/u4:6/9270 is trying to acquire lock:
ffff8880909c90d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff8880909c90d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078

but task is already holding lock:
ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_tp_rxtimer+0x1c0/0x36b net/can/j1939/transport.c:1243

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&priv->active_session_list_lock){+.-.}-{2:2}:
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
j1939_session_activate+0x43/0x4b0 net/can/j1939/transport.c:1554
j1939_sk_queue_activate_next_locked net/can/j1939/socket.c:181 [inline]
j1939_sk_queue_activate_next+0x29b/0x460 net/can/j1939/socket.c:205
j1939_session_deactivate_activate_next net/can/j1939/transport.c:1101 [inline]
j1939_session_completed+0x80/0x120 net/can/j1939/transport.c:1214
j1939_xtp_rx_eoma_one net/can/j1939/transport.c:1385 [inline]
j1939_xtp_rx_eoma+0x2a6/0x5f0 net/can/j1939/transport.c:1400
j1939_tp_cmd_recv net/can/j1939/transport.c:2079 [inline]
j1939_tp_recv+0x430/0xb40 net/can/j1939/transport.c:2118
j1939_can_recv+0x6d7/0x930 net/can/j1939/main.c:101
deliver net/can/af_can.c:574 [inline]
can_rcv_filter+0x5d4/0x8d0 net/can/af_can.c:608
can_receive+0x31d/0x580 net/can/af_can.c:665
can_rcv+0x120/0x1c0 net/can/af_can.c:696
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5436
__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5550
process_backlog+0x2a5/0x6c0 net/core/dev.c:6427
__napi_poll+0xaf/0x440 net/core/dev.c:6986
napi_poll net/core/dev.c:7053 [inline]
net_rx_action+0x801/0xb40 net/core/dev.c:7140
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
run_ksoftirqd kernel/softirq.c:920 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:912
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #1 (&jsk->sk_session_queue_lock){+.-.}-{2:2}:
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
j1939_sk_queue_drop_all+0x40/0x2f0 net/can/j1939/socket.c:139
j1939_sk_netdev_event_netdown+0x7b/0x160 net/can/j1939/socket.c:1272
j1939_netdev_notify+0x199/0x1d0 net/can/j1939/main.c:362
notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1996
call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
call_netdevice_notifiers net/core/dev.c:2022 [inline]
dev_close_many+0x2ff/0x620 net/core/dev.c:1597
unregister_netdevice_many+0x3ff/0x1790 net/core/dev.c:11020
rtnl_delete_link net/core/rtnetlink.c:3063 [inline]
rtnl_dellink+0x354/0xa80 net/core/rtnetlink.c:3115
rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5572
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:724
____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
___sys_sendmsg+0xf3/0x170 net/socket.c:2463
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (&priv->j1939_socks_lock){+.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078
__j1939_session_cancel+0x3b9/0x460 net/can/j1939/transport.c:1124
j1939_tp_rxtimer+0x2a8/0x36b net/can/j1939/transport.c:1250
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1766
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:636
irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
batadv_nc_process_nc_paths.part.0+0x24e/0x3c0 net/batman-adv/network-coding.c:685
batadv_nc_process_nc_paths net/batman-adv/network-coding.c:681 [inline]
batadv_nc_worker+0xc46/0xfa0 net/batman-adv/network-coding.c:730
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

other info that might help us debug this:

Chain exists of:
&priv->j1939_socks_lock --> &jsk->sk_session_queue_lock --> &priv->active_session_list_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&priv->active_session_list_lock);
lock(&jsk->sk_session_queue_lock);
lock(&priv->active_session_list_lock);
lock(&priv->j1939_socks_lock);

*** DEADLOCK ***

3 locks held by kworker/u4:6/9270:
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline]
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:634 [inline]
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
#0: ffff888025be1938 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work+0x8a3/0x16b0 kernel/workqueue.c:2268
#1: ffffc9000451fdb0 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work+0x8d7/0x16b0 kernel/workqueue.c:2272
#2: ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
#2: ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
#2: ffff8880909c9088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_tp_rxtimer+0x1c0/0x36b net/can/j1939/transport.c:1243

stack backtrace:
CPU: 0 PID: 9270 Comm: kworker/u4:6 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2131
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add kernel/locking/lockdep.c:3174 [inline]
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x2a07/0x54a0 kernel/locking/lockdep.c:5015
lock_acquire kernel/locking/lockdep.c:5625 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:368 [inline]
j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078
__j1939_session_cancel+0x3b9/0x460 net/can/j1939/transport.c:1124
j1939_tp_rxtimer+0x2a8/0x36b net/can/j1939/transport.c:1250
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1766
__do_softirq+0x29b/0x9c2 kernel/softirq.c:558
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:636
irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097
</IRQ>
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:batadv_nc_process_nc_paths.part.0+0x24e/0x3c0 net/batman-adv/network-coding.c:685
Code: c6 43 5f d2 88 48 c7 c7 60 fe 97 8b e8 0b f0 88 f8 48 8b 44 24 28 83 44 24 14 01 0f b6 00 84 c0 74 08 3c 03 0f 8e 2e 01 00 00 <48> 8b 44 24 18 44 8b 7c 24 14 8b 58 10 44 89 fe 89 df e8 4b a6 a3
RSP: 0018:ffffc9000451fc20 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffc9000451fba8
RDX: 1ffff11004b9fbed RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88806ecd5790 R14: ffff88806ecd4c80 R15: 0000000000000400
batadv_nc_process_nc_paths net/batman-adv/network-coding.c:681 [inline]
batadv_nc_worker+0xc46/0xfa0 net/batman-adv/network-coding.c:730
process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
vcan0: j1939_tp_rxtimer: 0xffff8881480fd400: abort rx timeout. Force session deactivation
----------------
Code disassembly (best guess), 5 bytes skipped:
0: 48 c7 c7 60 fe 97 8b mov $0xffffffff8b97fe60,%rdi
7: e8 0b f0 88 f8 callq 0xf888f017
c: 48 8b 44 24 28 mov 0x28(%rsp),%rax
11: 83 44 24 14 01 addl $0x1,0x14(%rsp)
16: 0f b6 00 movzbl (%rax),%eax
19: 84 c0 test %al,%al
1b: 74 08 je 0x25
1d: 3c 03 cmp $0x3,%al
1f: 0f 8e 2e 01 00 00 jle 0x153
* 25: 48 8b 44 24 18 mov 0x18(%rsp),%rax <-- trapping instruction
2a: 44 8b 7c 24 14 mov 0x14(%rsp),%r15d
2f: 8b 58 10 mov 0x10(%rax),%ebx
32: 44 89 fe mov %r15d,%esi
35: 89 df mov %ebx,%edi
37: e8 .byte 0xe8
38: 4b a6 rex.WXB cmpsb %es:(%rdi),%ds:(%rsi)
3a: a3 .byte 0xa3


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 24625f7d91fb Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1391e2d7f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=70e1a4d352a3c6ae

dashboard link: https://syzkaller.appspot.com/bug?extid=ee1cd780f69483a8616b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=163611bff00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=157d01e7f00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ee1cd7...@syzkaller.appspotmail.com

vcan0: j1939_tp_rxtimer: 0xffff88814717a000: rx timeout, send abort
vcan0: j1939_tp_rxtimer: 0xffff88807b7b3800: rx timeout, send abort

======================================================
WARNING: possible circular locking dependency detected

5.19.0-rc2-syzkaller-00049-g24625f7d91fb #0 Not tainted
------------------------------------------------------
swapper/0/0 is trying to acquire lock:
ffff8880777290d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
ffff8880777290d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078

but task is already holding lock:

ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_tp_rxtimer+0xe5/0x220 net/can/j1939/transport.c:1240

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&priv->active_session_list_lock){+.-.}-{2:2}:

__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:354 [inline]
j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
j1939_session_activate+0x43/0x4b0 net/can/j1939/transport.c:1553

j1939_sk_queue_activate_next_locked net/can/j1939/socket.c:181 [inline]
j1939_sk_queue_activate_next+0x29b/0x460 net/can/j1939/socket.c:205
j1939_session_deactivate_activate_next net/can/j1939/transport.c:1101 [inline]

j1939_session_completed+0x19a/0x1f0 net/can/j1939/transport.c:1214
j1939_xtp_rx_eoma_one net/can/j1939/transport.c:1384 [inline]
j1939_xtp_rx_eoma+0x2a6/0x5f0 net/can/j1939/transport.c:1399
j1939_tp_cmd_recv net/can/j1939/transport.c:2088 [inline]
j1939_tp_recv+0x930/0xcb0 net/can/j1939/transport.c:2133
j1939_can_recv+0x6ff/0x9a0 net/can/j1939/main.c:108

deliver net/can/af_can.c:574 [inline]
can_rcv_filter+0x5d4/0x8d0 net/can/af_can.c:608
can_receive+0x31d/0x580 net/can/af_can.c:665
can_rcv+0x120/0x1c0 net/can/af_can.c:696

__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5478
__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5592
process_backlog+0x3a0/0x7c0 net/core/dev.c:5920
__napi_poll+0xb3/0x6e0 net/core/dev.c:6486
napi_poll net/core/dev.c:6553 [inline]
net_rx_action+0x9c1/0xd90 net/core/dev.c:6664
__do_softirq+0x29b/0x9c2 kernel/softirq.c:571
run_ksoftirqd kernel/softirq.c:934 [inline]
run_ksoftirqd+0x2d/0x60 kernel/softirq.c:926
smpboot_thread_fn+0x645/0x9c0 kernel/smpboot.c:164
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

-> #1 (&jsk->sk_session_queue_lock){+.-.}-{2:2}:

__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:354 [inline]

j1939_sk_queue_drop_all+0x40/0x2f0 net/can/j1939/socket.c:139
j1939_sk_netdev_event_netdown+0x7b/0x160 net/can/j1939/socket.c:1272

j1939_netdev_notify+0x199/0x1d0 net/can/j1939/main.c:372
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1943
call_netdevice_notifiers_extack net/core/dev.c:1981 [inline]
call_netdevice_notifiers net/core/dev.c:1995 [inline]
__dev_notify_flags+0x1da/0x2b0 net/core/dev.c:8571
dev_change_flags+0x112/0x170 net/core/dev.c:8607
do_setlink+0x961/0x3bb0 net/core/rtnetlink.c:2780
__rtnl_newlink+0xd6a/0x17e0 net/core/rtnetlink.c:3546
rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3593
rtnetlink_rcv_msg+0x43a/0xc90 net/core/rtnetlink.c:6089
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2492
___sys_sendmsg+0xf3/0x170 net/socket.c:2546
__sys_sendmsg net/socket.c:2575 [inline]
__do_sys_sendmsg net/socket.c:2584 [inline]
__se_sys_sendmsg net/socket.c:2582 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2582

do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x46/0xb0

-> #0 (&priv->j1939_socks_lock){+.-.}-{2:2}:

check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5665 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:354 [inline]

j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078
__j1939_session_cancel+0x3b9/0x460 net/can/j1939/transport.c:1124

j1939_tp_rxtimer.cold+0x1f6/0x24f net/can/j1939/transport.c:1249

__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1766

__do_softirq+0x29b/0x9c2 kernel/softirq.c:571
invoke_softirq kernel/softirq.c:445 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1106
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:649
native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
acpi_idle_do_entry+0x1c9/0x240 drivers/acpi/processor_idle.c:554
acpi_idle_enter+0x369/0x510 drivers/acpi/processor_idle.c:691
cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237
cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:236 [inline]
do_idle+0x3e8/0x590 kernel/sched/idle.c:303
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400
rest_init+0x169/0x270 init/main.c:726
arch_call_rest_init+0xf/0x14 init/main.c:882
start_kernel+0x46e/0x48f init/main.c:1137
secondary_startup_64_no_verify+0xce/0xdb

other info that might help us debug this:

Chain exists of:
&priv->j1939_socks_lock --> &jsk->sk_session_queue_lock --> &priv->active_session_list_lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&priv->active_session_list_lock);
lock(&jsk->sk_session_queue_lock);
lock(&priv->active_session_list_lock);
lock(&priv->j1939_socks_lock);

*** DEADLOCK ***

1 lock held by swapper/0/0:
#0: ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
#0: ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
#0: ffff888077729088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_tp_rxtimer+0xe5/0x220 net/can/j1939/transport.c:1240

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc2-syzkaller-00049-g24625f7d91fb #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106

check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3829 [inline]
__lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053
lock_acquire kernel/locking/lockdep.c:5665 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:354 [inline]

j1939_sk_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078
__j1939_session_cancel+0x3b9/0x460 net/can/j1939/transport.c:1124

j1939_tp_rxtimer.cold+0x1f6/0x24f net/can/j1939/transport.c:1249

__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x17b/0x360 kernel/time/hrtimer.c:1766

__do_softirq+0x29b/0x9c2 kernel/softirq.c:571
invoke_softirq kernel/softirq.c:445 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1106
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
RIP: 0010:acpi_idle_do_entry+0x1c9/0x240 drivers/acpi/processor_idle.c:554
Code: 89 de e8 4a 53 00 f8 84 db 75 98 e8 41 57 00 f8 e8 2c a7 06 f8 66 90 e8 35 57 00 f8 0f 00 2d 2e f0 b9 00 e8 29 57 00 f8 fb f4 <9c> 5b 81 e3 00 02 00 00 fa 31 ff 48 89 de e8 74 53 00 f8 48 85 db
RSP: 0018:ffffffff8ba07d38 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffffffff8babc940 RSI: ffffffff897a1ad7 RDI: 0000000000000000
RBP: ffff888017071064 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000001
R13: ffff888017071000 R14: ffff888017071064 R15: ffff88801b1cd804
acpi_idle_enter+0x369/0x510 drivers/acpi/processor_idle.c:691
cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237
cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:236 [inline]
do_idle+0x3e8/0x590 kernel/sched/idle.c:303
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400
rest_init+0x169/0x270 init/main.c:726
arch_call_rest_init+0xf/0x14 init/main.c:882
start_kernel+0x46e/0x48f init/main.c:1137
secondary_startup_64_no_verify+0xce/0xdb
</TASK>
vcan0: j1939_xtp_rx_abort_one: 0xffff88814717a000: 0x00000: (3) A timeout occurred and this is the connection abort to close the session.
vcan0: j1939_xtp_rx_abort_one: 0xffff88807b7b3800: 0x00000: (3) A timeout occurred and this is the connection abort to close the session.
----------------
Code disassembly (best guess):
0: 89 de mov %ebx,%esi
2: e8 4a 53 00 f8 callq 0xf8005351
7: 84 db test %bl,%bl
9: 75 98 jne 0xffffffa3
b: e8 41 57 00 f8 callq 0xf8005751
10: e8 2c a7 06 f8 callq 0xf806a741
15: 66 90 xchg %ax,%ax
17: e8 35 57 00 f8 callq 0xf8005751
1c: 0f 00 2d 2e f0 b9 00 verw 0xb9f02e(%rip) # 0xb9f051
23: e8 29 57 00 f8 callq 0xf8005751
28: fb sti
29: f4 hlt
* 2a: 9c pushfq <-- trapping instruction
2b: 5b pop %rbx
2c: 81 e3 00 02 00 00 and $0x200,%ebx
32: fa cli
33: 31 ff xor %edi,%edi
35: 48 89 de mov %rbx,%rsi
38: e8 74 53 00 f8 callq 0xf80053b1
3d: 48 85 db test %rbx,%rbx

[Hillf Danton]

On Tue, 14 Jun 2022 15:53:23 -0700

To fix the deadlock, split __j1939_session_cancel() into two parts, and
info the callers to do the bottom half.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 24625f7d91fb

diff -pur a/net/can/j1939/transport.c b/net/can/j1939/transport.c
--- a/net/can/j1939/transport.c 2022-06-15 18:48:27.235848700 +0800
+++ b/net/can/j1939/transport.c 2022-06-15 18:54:11.242804700 +0800
@@ -1101,7 +1101,7 @@ j1939_session_deactivate_activate_next(s
j1939_sk_queue_activate_next(session);
}

-static void __j1939_session_cancel(struct j1939_session *session,
+static int __j1939_session_cancel(struct j1939_session *session,
enum j1939_xtp_abort err)
{
struct j1939_priv *priv = session->priv;
@@ -1118,24 +1118,29 @@ static void __j1939_session_cancel(struc
err, session->skcb.addr.pgn);
}

- if (session->sk)
+ if (session->sk) {
j1939_sk_send_loop_abort(session->sk, session->err);
- else
- j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
+ return 0;
+ } else
+ return 1;
}

static void j1939_session_cancel(struct j1939_session *session,
enum j1939_xtp_abort err)
{
+ int errq = 0;
j1939_session_list_lock(session->priv);

if (session->state >= J1939_SESSION_ACTIVE &&
session->state < J1939_SESSION_WAITING_ABORT) {
j1939_tp_set_rxtimeout(session, J1939_XTP_ABORT_TIMEOUT_MS);
- __j1939_session_cancel(session, err);
+ errq = __j1939_session_cancel(session, err);
}

j1939_session_list_unlock(session->priv);
+
+ if (errq)
+ j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
}

static enum hrtimer_restart j1939_tp_txtimer(struct hrtimer *hrtimer)
@@ -1237,6 +1242,7 @@ static enum hrtimer_restart j1939_tp_rxt
session->err = -ETIME;
j1939_session_deactivate(session);
} else {
+ int errq = 0;
j1939_session_list_lock(session->priv);
if (session->state >= J1939_SESSION_ACTIVE &&
session->state < J1939_SESSION_ACTIVE_MAX) {
@@ -1246,9 +1252,12 @@ static enum hrtimer_restart j1939_tp_rxt
hrtimer_start(&session->rxtimer,
ms_to_ktime(J1939_XTP_ABORT_TIMEOUT_MS),
HRTIMER_MODE_REL_SOFT);
- __j1939_session_cancel(session, J1939_XTP_ABORT_TIMEOUT);
+ errq = __j1939_session_cancel(session, J1939_XTP_ABORT_TIMEOUT);
}
j1939_session_list_unlock(session->priv);
+
+ if (errq)
+ j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT);
}

j1939_session_put(session);
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+ee1cd7...@syzkaller.appspotmail.com

Tested on:

commit: 24625f7d Merge tag 'for-linus' of git://git.kernel.org..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=17d77f10080000

kernel config: https://syzkaller.appspot.com/x/.config?x=70e1a4d352a3c6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=ee1cd780f69483a8616b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=10b51fbff00000

Note: testing is done by a robot and is best-effort only.