Subject: Re: [syzbot] [can?] possible deadlock in j1939_sk_errqueue (2)

From: syzbot <[email-masked]>
Date: Mon, 10 Jul 2023 10:53:57 -0700

syzbot has found a reproducer for the following issue on:

HEAD commit:    e40939bbfc68 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17ce67d8a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c84f463eb74eab24
dashboard link: https://syzkaller.appspot.com/bug?extid=1591462f226d9cbf0564
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1580fc5ca80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=178f78d4a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/257596b75aaf/disk-e40939bb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9c75b8d61081/vmlinux-e40939bb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f0233129f4f/Image-e40939bb.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc7-syzkaller-ge40939bbfc68 #0 Not tainted
------------------------------------------------------
syz-executor375/6045 is trying to acquire lock:
ffff0000d2e690d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline]
ffff0000d2e690d0 (&priv->j1939_socks_lock){+.-.}-{2:2}, at: j1939_sk_errqueue+0x90/0x144 net/can/j1939/socket.c:1081

but task is already holding lock:
ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline]
ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_cancel_active_session+0x54/0x414 net/can/j1939/transport.c:2183

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+0x48/0x60 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:355 [inline]
       j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
       j1939_session_activate+0x60/0x378 net/can/j1939/transport.c:1564
       j1939_sk_queue_activate_next_locked net/can/j1939/socket.c:181 [inline]
       j1939_sk_queue_activate_next+0x230/0x3b4 net/can/j1939/socket.c:208
       j1939_session_deactivate_activate_next net/can/j1939/transport.c:1108 [inline]
       j1939_session_completed net/can/j1939/transport.c:1222 [inline]
       j1939_xtp_rx_eoma_one net/can/j1939/transport.c:1395 [inline]
       j1939_xtp_rx_eoma+0x2c0/0x4c0 net/can/j1939/transport.c:1410
       j1939_tp_cmd_recv net/can/j1939/transport.c:2099 [inline]
       j1939_tp_recv+0x714/0xe14 net/can/j1939/transport.c:2144
       j1939_can_recv+0x5bc/0x930 net/can/j1939/main.c:112
       deliver net/can/af_can.c:572 [inline]
       can_rcv_filter+0x308/0x714 net/can/af_can.c:606
       can_receive+0x338/0x498 net/can/af_can.c:663
       can_rcv+0x128/0x23c net/can/af_can.c:687
       __netif_receive_skb_one_core net/core/dev.c:5493 [inline]
       __netif_receive_skb+0x18c/0x400 net/core/dev.c:5607
       process_backlog+0x3c0/0x70c net/core/dev.c:5935
       __napi_poll+0xb4/0x648 net/core/dev.c:6498
       napi_poll net/core/dev.c:6565 [inline]
       net_rx_action+0x5e4/0xdc4 net/core/dev.c:6698
       __do_softirq+0x2d0/0xd54 kernel/softirq.c:571
       run_ksoftirqd+0x6c/0x158 kernel/softirq.c:939
       smpboot_thread_fn+0x4b0/0x920 kernel/smpboot.c:164
       kthread+0x288/0x310 kernel/kthread.c:379
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:853

-> #1 (&jsk->sk_session_queue_lock){+.-.}-{2:2}:
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:355 [inline]
       j1939_sk_queue_drop_all+0x4c/0x200 net/can/j1939/socket.c:139
       j1939_sk_netdev_event_netdown+0xe0/0x144 net/can/j1939/socket.c:1280
       j1939_netdev_notify+0xf0/0x144 net/can/j1939/main.c:381
       notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93
       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461
       __dev_notify_flags+0x2bc/0x544
       dev_change_flags+0xd0/0x15c net/core/dev.c:8645
       do_setlink+0xc68/0x35c8 net/core/rtnetlink.c:2867
       __rtnl_newlink net/core/rtnetlink.c:3648 [inline]
       rtnl_newlink+0x1354/0x1b1c net/core/rtnetlink.c:3695
       rtnetlink_rcv_msg+0x744/0xdb8 net/core/rtnetlink.c:6417
       netlink_rcv_skb+0x214/0x3c4 net/netlink/af_netlink.c:2546
       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6435
       netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
       netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1365
       netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1913
       sock_sendmsg_nosec net/socket.c:724 [inline]
       sock_sendmsg net/socket.c:747 [inline]
       ____sys_sendmsg+0x568/0x81c net/socket.c:2503
       ___sys_sendmsg net/socket.c:2557 [inline]
       __sys_sendmsg+0x26c/0x33c net/socket.c:2586
       __do_sys_sendmsg net/socket.c:2595 [inline]
       __se_sys_sendmsg net/socket.c:2593 [inline]
       __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2593
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
       el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

-> #0 (&priv->j1939_socks_lock){+.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3113 [inline]
       check_prevs_add kernel/locking/lockdep.c:3232 [inline]
       validate_chain kernel/locking/lockdep.c:3847 [inline]
       __lock_acquire+0x3308/0x7604 kernel/locking/lockdep.c:5088
       lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5705
       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
       _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178
       spin_lock_bh include/linux/spinlock.h:355 [inline]
       j1939_sk_errqueue+0x90/0x144 net/can/j1939/socket.c:1081
       __j1939_session_release net/can/j1939/transport.c:294 [inline]
       kref_put include/linux/kref.h:65 [inline]
       j1939_session_put+0xf0/0x4b4 net/can/j1939/transport.c:299
       j1939_session_deactivate_locked net/can/j1939/transport.c:1086 [inline]
       j1939_cancel_active_session+0x2ec/0x414 net/can/j1939/transport.c:2194
       j1939_netdev_notify+0xe8/0x144 net/can/j1939/main.c:380
       notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93
       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461
       __dev_notify_flags+0x2bc/0x544
       dev_change_flags+0xd0/0x15c net/core/dev.c:8645
       do_setlink+0xc68/0x35c8 net/core/rtnetlink.c:2867
       __rtnl_newlink net/core/rtnetlink.c:3648 [inline]
       rtnl_newlink+0x1354/0x1b1c net/core/rtnetlink.c:3695
       rtnetlink_rcv_msg+0x744/0xdb8 net/core/rtnetlink.c:6417
       netlink_rcv_skb+0x214/0x3c4 net/netlink/af_netlink.c:2546
       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6435
       netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
       netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1365
       netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1913
       sock_sendmsg_nosec net/socket.c:724 [inline]
       sock_sendmsg net/socket.c:747 [inline]
       ____sys_sendmsg+0x568/0x81c net/socket.c:2503
       ___sys_sendmsg net/socket.c:2557 [inline]
       __sys_sendmsg+0x26c/0x33c net/socket.c:2586
       __do_sys_sendmsg net/socket.c:2595 [inline]
       __se_sys_sendmsg net/socket.c:2593 [inline]
       __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2593
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
       el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

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 ***

2 locks held by syz-executor375/6045:
 #0: ffff80009080db68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffff80009080db68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x700/0xdb8 net/core/rtnetlink.c:6414
 #1: ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline]
 #1: ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_session_list_lock net/can/j1939/transport.c:238 [inline]
 #1: ffff0000d2e69088 (&priv->active_session_list_lock){+.-.}-{2:2}, at: j1939_cancel_active_session+0x54/0x414 net/can/j1939/transport.c:2183

stack backtrace:
CPU: 1 PID: 6045 Comm: syz-executor375 Not tainted 6.4.0-rc7-syzkaller-ge40939bbfc68 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
 show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2066
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2188
 check_prev_add kernel/locking/lockdep.c:3113 [inline]
 check_prevs_add kernel/locking/lockdep.c:3232 [inline]
 validate_chain kernel/locking/lockdep.c:3847 [inline]
 __lock_acquire+0x3308/0x7604 kernel/locking/lockdep.c:5088
 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5705
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x48/0x60 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:355 [inline]
 j1939_sk_errqueue+0x90/0x144 net/can/j1939/socket.c:1081
 __j1939_session_release net/can/j1939/transport.c:294 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0xf0/0x4b4 net/can/j1939/transport.c:299
 j1939_session_deactivate_locked net/can/j1939/transport.c:1086 [inline]
 j1939_cancel_active_session+0x2ec/0x414 net/can/j1939/transport.c:2194
 j1939_netdev_notify+0xe8/0x144 net/can/j1939/main.c:380
 notifier_call_chain+0x1a4/0x510 kernel/notifier.c:93
 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:461
 __dev_notify_flags+0x2bc/0x544
 dev_change_flags+0xd0/0x15c net/core/dev.c:8645
 do_setlink+0xc68/0x35c8 net/core/rtnetlink.c:2867
 __rtnl_newlink net/core/rtnetlink.c:3648 [inline]
 rtnl_newlink+0x1354/0x1b1c net/core/rtnetlink.c:3695
 rtnetlink_rcv_msg+0x744/0xdb8 net/core/rtnetlink.c:6417
 netlink_rcv_skb+0x214/0x3c4 net/netlink/af_netlink.c:2546
 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6435
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x568/0x81c net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x26c/0x33c net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2593
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x244 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:191
 el0_svc+0x4c/0x160 arch/arm64/kernel/entry-common.c:647
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

---
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