Re: [syzbot] possible deadlock in j1939_sk_queue_drop_all

From: syzbot
Date: Sat Jun 04 2022 - 02:12:39 EST

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Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in j1939_sk_queue_drop_all

======================================================
WARNING: possible circular locking dependency detected
5.18.0-syzkaller-12234-g50fd82b3a9a9-dirty #0 Not tainted
------------------------------------------------------
syz-executor.0/4079 is trying to acquire lock:
ffff88807462f5c8 (&jsk->sk_session_queue_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
ffff88807462f5c8 (&jsk->sk_session_queue_lock){+.-.}-{2:2}, at: j1939_sk_queue_drop_all+0x40/0x2f0 net/can/j1939/socket.c:139

but task is already holding lock:
ffff888022b210d0
(&priv->j1939_socks_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
(&priv->j1939_socks_lock){+.-.}-{2:2}, at: j1939_sk_netdev_event_netdown+0x28/0x160 net/can/j1939/socket.c:1266

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2
(&priv->j1939_socks_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_errqueue+0x9f/0x1a0 net/can/j1939/socket.c:1078
j1939_session_destroy+0x301/0x3d0 net/can/j1939/transport.c:269
__j1939_session_release net/can/j1939/transport.c:288 [inline]
kref_put include/linux/kref.h:65 [inline]
j1939_session_put net/can/j1939/transport.c:293 [inline]
j1939_session_deactivate_locked net/can/j1939/transport.c:1075 [inline]
j1939_session_deactivate_locked+0x293/0x340 net/can/j1939/transport.c:1063
j1939_cancel_active_session+0x184/0x370 net/can/j1939/transport.c:2197
j1939_netdev_notify+0x191/0x1d0 net/can/j1939/main.c:371
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

-> #1 (&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:1567
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:1219
j1939_xtp_rx_eoma_one net/can/j1939/transport.c:1398 [inline]
j1939_xtp_rx_eoma+0x2a6/0x5f0 net/can/j1939/transport.c:1413
j1939_tp_cmd_recv net/can/j1939/transport.c:2102 [inline]
j1939_tp_recv+0x930/0xcb0 net/can/j1939/transport.c:2147
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

-> #0 (&jsk->sk_session_queue_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_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

other info that might help us debug this:

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

Possible unsafe locking scenario:

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

*** DEADLOCK ***

2 locks held by syz-executor.0/4079:
#0: ffffffff8d5937e8 (rtnl_mutex
){+.+.}-{3:3}
, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
, at: rtnetlink_rcv_msg+0x3e5/0xc90 net/core/rtnetlink.c:6086
#1: ffff888022b210d0 (&priv->j1939_socks_lock
){+.-.}-{2:2}
, at: spin_lock_bh include/linux/spinlock.h:354 [inline]
, at: j1939_sk_netdev_event_netdown+0x28/0x160 net/can/j1939/socket.c:1266

stack backtrace:
CPU: 0 PID: 4079 Comm: syz-executor.0 Not tainted 5.18.0-syzkaller-12234-g50fd82b3a9a9-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__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_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
RIP: 0033:0x7f106a489109
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f106b644168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f106a59c030 RCX: 00007f106a489109
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000000000005
RBP: 00007f106a4e308d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcb00ebfaf R14: 00007f106b644300 R15: 0000000000022000
</TASK>
A link change request failed with some changes committed already. Interface vxcan0 may have been left with an inconsistent configuration, please check.

Tested on:

commit: 50fd82b3 Merge tag 'docs-5.19-2' of git://git.lwn.net/..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=14f3f82bf00000
kernel config: https://syzkaller.appspot.com/x/.config?x=fc5a30a131480a80
dashboard link: https://syzkaller.appspot.com/bug?extid=3bd970a1887812621b4c
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=15ee5177f00000

Next message: Juergen Gross: "[GIT PULL] xen: branch for v5.19-rc1b"
Previous message: Christophe JAILLET: "[PATCH] nfp: Remove kernel.h when not needed"
In reply to: syzbot: "Re: [syzbot] possible deadlock in j1939_sk_queue_drop_all"
Next in thread: syzbot: "Re: [syzbot] possible deadlock in j1939_sk_queue_drop_all"
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