syzbot


possible deadlock in ppp_input

Status: upstream: reported on 2024/09/25 02:52
Reported-by: syzbot+d0a2a8574bdabda16521@syzkaller.appspotmail.com
First crash: 87d, last: 66d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ppp_input ppp 197 74d 95d 0/28 auto-obsoleted due to no activity on 2024/12/17 07:14
linux-5.15 possible deadlock in ppp_input 17 65d 98d 0/3 upstream: reported on 2024/09/14 14:35

Sample crash report:
========================================================
WARNING: possible irq lock inversion dependency detected
6.1.112-syzkaller #0 Not tainted
--------------------------------------------------------
syz.0.805/7697 just changed the state of lock:
ffff888061d839e0 (&pch->downl){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888061d839e0 (&pch->downl){+.+.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
ffff888061d839e0 (&pch->downl){+.+.}-{2:2}, at: ppp_input+0x185/0xa00 drivers/net/ppp/ppp_generic.c:2304
but this lock was taken by another, SOFTIRQ-READ-safe lock in the past:
 (&pch->upl){++.-}-{2:2}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Chain exists of:
  &pch->upl --> &ppp->rlock --> &pch->downl

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pch->downl);
                               local_irq_disable();
                               lock(&pch->upl);
                               lock(&ppp->rlock);
  <Interrupt>
    lock(&pch->upl);

 *** DEADLOCK ***

2 locks held by syz.0.805/7697:
 #0: ffff8880263e2130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1748 [inline]
 #0: ffff8880263e2130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppoe_sendmsg+0x4d/0x740 drivers/net/ppp/pppoe.c:849
 #1: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2267 [inline]
 #1: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: ppp_input+0x51/0xa00 drivers/net/ppp/ppp_generic.c:2304

the shortest dependencies between 2nd lock and 1st lock:
   -> (&pch->upl){++.-}-{2:2} {
      HARDIRQ-ON-W at:
                          lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                          __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
                          _raw_write_lock_bh+0x31/0x40 kernel/locking/spinlock.c:334
                          ppp_disconnect_channel+0x2f/0x2d0 drivers/net/ppp/ppp_generic.c:3522
                          ppp_unregister_channel+0xb5/0x2f0 drivers/net/ppp/ppp_generic.c:2996
                          ppp_asynctty_close+0xed/0x180 drivers/net/ppp/ppp_async.c:237
                          tty_ldisc_kill+0xa6/0x1a0 drivers/tty/tty_ldisc.c:614
                          tty_ldisc_release+0x19d/0x200 drivers/tty/tty_ldisc.c:782
                          tty_release_struct+0x27/0xd0 drivers/tty/tty_io.c:1689
                          tty_release+0xcfb/0x12a0 drivers/tty/tty_io.c:1860
                          __fput+0x3f6/0x8d0 fs/file_table.c:320
                          task_work_run+0x246/0x300 kernel/task_work.c:203
                          resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
                          exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
                          exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
                          __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
                          syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
                          do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
                          entry_SYSCALL_64_after_hwframe+0x68/0xd2
      HARDIRQ-ON-R at:
                          lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                          __raw_read_lock_bh include/linux/rwlock_api_smp.h:176 [inline]
                          _raw_read_lock_bh+0x39/0x50 kernel/locking/spinlock.c:252
                          ppp_input_error+0x5c/0x1a0 drivers/net/ppp/ppp_generic.c:2344
                          ppp_sync_process+0x86/0x170 drivers/net/ppp/ppp_synctty.c:495
                          tasklet_action_common+0x3cb/0x4a0
                          handle_softirqs+0x2ee/0xa40 kernel/softirq.c:571
                          run_ksoftirqd+0xc6/0x120 kernel/softirq.c:938
                          smpboot_thread_fn+0x52c/0xa30 kernel/smpboot.c:164
                          kthread+0x28d/0x320 kernel/kthread.c:376
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      IN-SOFTIRQ-R at:
                          lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                          __raw_read_lock_bh include/linux/rwlock_api_smp.h:176 [inline]
                          _raw_read_lock_bh+0x39/0x50 kernel/locking/spinlock.c:252
                          ppp_input_error+0x5c/0x1a0 drivers/net/ppp/ppp_generic.c:2344
                          ppp_sync_process+0x86/0x170 drivers/net/ppp/ppp_synctty.c:495
                          tasklet_action_common+0x3cb/0x4a0
                          handle_softirqs+0x2ee/0xa40 kernel/softirq.c:571
                          run_ksoftirqd+0xc6/0x120 kernel/softirq.c:938
                          smpboot_thread_fn+0x52c/0xa30 kernel/smpboot.c:164
                          kthread+0x28d/0x320 kernel/kthread.c:376
                          ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
      INITIAL USE at:
                         lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                         __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
                         _raw_write_lock_bh+0x31/0x40 kernel/locking/spinlock.c:334
                         ppp_disconnect_channel+0x2f/0x2d0 drivers/net/ppp/ppp_generic.c:3522
                         ppp_unregister_channel+0xb5/0x2f0 drivers/net/ppp/ppp_generic.c:2996
                         ppp_asynctty_close+0xed/0x180 drivers/net/ppp/ppp_async.c:237
                         tty_ldisc_kill+0xa6/0x1a0 drivers/tty/tty_ldisc.c:614
                         tty_ldisc_release+0x19d/0x200 drivers/tty/tty_ldisc.c:782
                         tty_release_struct+0x27/0xd0 drivers/tty/tty_io.c:1689
                         tty_release+0xcfb/0x12a0 drivers/tty/tty_io.c:1860
                         __fput+0x3f6/0x8d0 fs/file_table.c:320
                         task_work_run+0x246/0x300 kernel/task_work.c:203
                         resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
                         exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
                         exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
                         __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
                         syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
                         do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
                         entry_SYSCALL_64_after_hwframe+0x68/0xd2
      INITIAL READ USE at:
                              lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                              __raw_read_lock_bh include/linux/rwlock_api_smp.h:176 [inline]
                              _raw_read_lock_bh+0x39/0x50 kernel/locking/spinlock.c:252
                              ppp_input_error+0x5c/0x1a0 drivers/net/ppp/ppp_generic.c:2344
                              ppp_sync_process+0x86/0x170 drivers/net/ppp/ppp_synctty.c:495
                              tasklet_action_common+0x3cb/0x4a0
                              handle_softirqs+0x2ee/0xa40 kernel/softirq.c:571
                              run_ksoftirqd+0xc6/0x120 kernel/softirq.c:938
                              smpboot_thread_fn+0x52c/0xa30 kernel/smpboot.c:164
                              kthread+0x28d/0x320 kernel/kthread.c:376
                              ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
    }
    ... key      at: [<ffffffff976dc060>] ppp_register_net_channel.__key.3+0x0/0x20
    ... acquired at:
   lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
   _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
   spin_lock_bh include/linux/spinlock.h:356 [inline]
   ppp_connect_channel+0x170/0x640 drivers/net/ppp/ppp_generic.c:3484
   ppp_ioctl+0xbe5/0x1c90 drivers/net/ppp/ppp_generic.c:759
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:870 [inline]
   __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
   do_syscall_x64 arch/x86/entry/common.c:51 [inline]
   do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
   entry_SYSCALL_64_after_hwframe+0x68/0xd2

  -> (&ppp->wlock){+...}-{2:2} {
     HARDIRQ-ON-W at:
                        lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                        __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                        _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                        spin_lock_bh include/linux/spinlock.h:356 [inline]
                        ppp_get_stats64+0xbf/0x290 drivers/net/ppp/ppp_generic.c:1539
                        dev_get_stats+0xa7/0x490 net/core/dev.c:10471
                        rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1244
                        rtnl_fill_ifinfo+0x18aa/0x2090 net/core/rtnetlink.c:1825
                        rtmsg_ifinfo_build_skb+0xdc/0x180 net/core/rtnetlink.c:3938
                        rtmsg_ifinfo_event net/core/rtnetlink.c:3970 [inline]
                        rtmsg_ifinfo+0x71/0x120 net/core/rtnetlink.c:3979
                        register_netdevice+0x13dc/0x1720 net/core/dev.c:10146
                        ppp_unit_register drivers/net/ppp/ppp_generic.c:1217 [inline]
                        ppp_dev_configure+0x850/0xab0 drivers/net/ppp/ppp_generic.c:1273
                        ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                        ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1058 [inline]
                        ppp_ioctl+0x702/0x1c90 drivers/net/ppp/ppp_generic.c:731
                        vfs_ioctl fs/ioctl.c:51 [inline]
                        __do_sys_ioctl fs/ioctl.c:870 [inline]
                        __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
                        do_syscall_x64 arch/x86/entry/common.c:51 [inline]
                        do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
                        entry_SYSCALL_64_after_hwframe+0x68/0xd2
     INITIAL USE at:
                       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                       _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                       spin_lock_bh include/linux/spinlock.h:356 [inline]
                       ppp_get_stats64+0xbf/0x290 drivers/net/ppp/ppp_generic.c:1539
                       dev_get_stats+0xa7/0x490 net/core/dev.c:10471
                       rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1244
                       rtnl_fill_ifinfo+0x18aa/0x2090 net/core/rtnetlink.c:1825
                       rtmsg_ifinfo_build_skb+0xdc/0x180 net/core/rtnetlink.c:3938
                       rtmsg_ifinfo_event net/core/rtnetlink.c:3970 [inline]
                       rtmsg_ifinfo+0x71/0x120 net/core/rtnetlink.c:3979
                       register_netdevice+0x13dc/0x1720 net/core/dev.c:10146
                       ppp_unit_register drivers/net/ppp/ppp_generic.c:1217 [inline]
                       ppp_dev_configure+0x850/0xab0 drivers/net/ppp/ppp_generic.c:1273
                       ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                       ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1058 [inline]
                       ppp_ioctl+0x702/0x1c90 drivers/net/ppp/ppp_generic.c:731
                       vfs_ioctl fs/ioctl.c:51 [inline]
                       __do_sys_ioctl fs/ioctl.c:870 [inline]
                       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
                       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
                       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
                       entry_SYSCALL_64_after_hwframe+0x68/0xd2
   }
   ... key      at: [<ffffffff976dc1a0>] ppp_dev_configure.__key.65+0x0/0x20
   ... acquired at:
   lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
   _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
   spin_lock_bh include/linux/spinlock.h:356 [inline]
   ppp_dev_uninit+0x68/0x1a0 drivers/net/ppp/ppp_generic.c:1572
   unregister_netdevice_many+0x11d7/0x17a0 net/core/dev.c:10899
   unregister_netdevice_queue+0x2e6/0x350 net/core/dev.c:10813
   unregister_netdevice include/linux/netdevice.h:3045 [inline]
   ppp_release+0xec/0x1f0 drivers/net/ppp/ppp_generic.c:408
   __fput+0x3f6/0x8d0 fs/file_table.c:320
   task_work_run+0x246/0x300 kernel/task_work.c:203
   resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
   exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
   exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
   __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
   syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
   do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
   entry_SYSCALL_64_after_hwframe+0x68/0xd2

 -> (&ppp->rlock){+...}-{2:2} {
    HARDIRQ-ON-W at:
                      lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                      __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                      _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                      spin_lock_bh include/linux/spinlock.h:356 [inline]
                      ppp_get_stats64+0x2f/0x290 drivers/net/ppp/ppp_generic.c:1534
                      dev_get_stats+0xa7/0x490 net/core/dev.c:10471
                      rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1244
                      rtnl_fill_ifinfo+0x18aa/0x2090 net/core/rtnetlink.c:1825
                      rtmsg_ifinfo_build_skb+0xdc/0x180 net/core/rtnetlink.c:3938
                      rtmsg_ifinfo_event net/core/rtnetlink.c:3970 [inline]
                      rtmsg_ifinfo+0x71/0x120 net/core/rtnetlink.c:3979
                      register_netdevice+0x13dc/0x1720 net/core/dev.c:10146
                      ppp_unit_register drivers/net/ppp/ppp_generic.c:1217 [inline]
                      ppp_dev_configure+0x850/0xab0 drivers/net/ppp/ppp_generic.c:1273
                      ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                      ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1058 [inline]
                      ppp_ioctl+0x702/0x1c90 drivers/net/ppp/ppp_generic.c:731
                      vfs_ioctl fs/ioctl.c:51 [inline]
                      __do_sys_ioctl fs/ioctl.c:870 [inline]
                      __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
                      do_syscall_x64 arch/x86/entry/common.c:51 [inline]
                      do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
                      entry_SYSCALL_64_after_hwframe+0x68/0xd2
    INITIAL USE at:
                     lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                     __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                     _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                     spin_lock_bh include/linux/spinlock.h:356 [inline]
                     ppp_get_stats64+0x2f/0x290 drivers/net/ppp/ppp_generic.c:1534
                     dev_get_stats+0xa7/0x490 net/core/dev.c:10471
                     rtnl_fill_stats+0x47/0x880 net/core/rtnetlink.c:1244
                     rtnl_fill_ifinfo+0x18aa/0x2090 net/core/rtnetlink.c:1825
                     rtmsg_ifinfo_build_skb+0xdc/0x180 net/core/rtnetlink.c:3938
                     rtmsg_ifinfo_event net/core/rtnetlink.c:3970 [inline]
                     rtmsg_ifinfo+0x71/0x120 net/core/rtnetlink.c:3979
                     register_netdevice+0x13dc/0x1720 net/core/dev.c:10146
                     ppp_unit_register drivers/net/ppp/ppp_generic.c:1217 [inline]
                     ppp_dev_configure+0x850/0xab0 drivers/net/ppp/ppp_generic.c:1273
                     ppp_create_interface drivers/net/ppp/ppp_generic.c:3348 [inline]
                     ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:1058 [inline]
                     ppp_ioctl+0x702/0x1c90 drivers/net/ppp/ppp_generic.c:731
                     vfs_ioctl fs/ioctl.c:51 [inline]
                     __do_sys_ioctl fs/ioctl.c:870 [inline]
                     __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
                     do_syscall_x64 arch/x86/entry/common.c:51 [inline]
                     do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
                     entry_SYSCALL_64_after_hwframe+0x68/0xd2
  }
  ... key      at: [<ffffffff976dc180>] ppp_dev_configure.__key+0x0/0x20
  ... acquired at:
   lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
   _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
   spin_lock_bh include/linux/spinlock.h:356 [inline]
   ppp_connect_channel+0x190/0x640 drivers/net/ppp/ppp_generic.c:3485
   ppp_ioctl+0xbe5/0x1c90 drivers/net/ppp/ppp_generic.c:759
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:870 [inline]
   __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
   do_syscall_x64 arch/x86/entry/common.c:51 [inline]
   do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
   entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> (&pch->downl){+.+.}-{2:2} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                    _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                    spin_lock_bh include/linux/spinlock.h:356 [inline]
                    ppp_unregister_channel+0x78/0x2f0 drivers/net/ppp/ppp_generic.c:2992
                    ppp_asynctty_close+0xed/0x180 drivers/net/ppp/ppp_async.c:237
                    tty_ldisc_kill+0xa6/0x1a0 drivers/tty/tty_ldisc.c:614
                    tty_ldisc_release+0x19d/0x200 drivers/tty/tty_ldisc.c:782
                    tty_release_struct+0x27/0xd0 drivers/tty/tty_io.c:1689
                    tty_release+0xcfb/0x12a0 drivers/tty/tty_io.c:1860
                    __fput+0x3f6/0x8d0 fs/file_table.c:320
                    task_work_run+0x246/0x300 kernel/task_work.c:203
                    resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
                    exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
                    exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
                    __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
                    syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
                    do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
                    entry_SYSCALL_64_after_hwframe+0x68/0xd2
   SOFTIRQ-ON-W at:
                    lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                    __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
                    _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
                    spin_lock include/linux/spinlock.h:351 [inline]
                    ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
                    ppp_input+0x185/0xa00 drivers/net/ppp/ppp_generic.c:2304
                    pppoe_rcv_core+0x112/0x300 drivers/net/ppp/pppoe.c:379
                    sk_backlog_rcv include/net/sock.h:1117 [inline]
                    __release_sock+0x198/0x4b0 net/core/sock.c:2936
                    release_sock+0x5d/0x1c0 net/core/sock.c:3500
                    pppoe_sendmsg+0xd1/0x740 drivers/net/ppp/pppoe.c:903
                    sock_sendmsg_nosec net/socket.c:718 [inline]
                    __sock_sendmsg net/socket.c:730 [inline]
                    ____sys_sendmsg+0x5a5/0x8f0 net/socket.c:2514
                    ___sys_sendmsg net/socket.c:2568 [inline]
                    __sys_sendmmsg+0x3ab/0x730 net/socket.c:2654
                    __do_sys_sendmmsg net/socket.c:2683 [inline]
                    __se_sys_sendmmsg net/socket.c:2680 [inline]
                    __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2680
                    do_syscall_x64 arch/x86/entry/common.c:51 [inline]
                    do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
                    entry_SYSCALL_64_after_hwframe+0x68/0xd2
   INITIAL USE at:
                   lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
                   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
                   _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                   spin_lock_bh include/linux/spinlock.h:356 [inline]
                   ppp_unregister_channel+0x78/0x2f0 drivers/net/ppp/ppp_generic.c:2992
                   ppp_asynctty_close+0xed/0x180 drivers/net/ppp/ppp_async.c:237
                   tty_ldisc_kill+0xa6/0x1a0 drivers/tty/tty_ldisc.c:614
                   tty_ldisc_release+0x19d/0x200 drivers/tty/tty_ldisc.c:782
                   tty_release_struct+0x27/0xd0 drivers/tty/tty_io.c:1689
                   tty_release+0xcfb/0x12a0 drivers/tty/tty_io.c:1860
                   __fput+0x3f6/0x8d0 fs/file_table.c:320
                   task_work_run+0x246/0x300 kernel/task_work.c:203
                   resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
                   exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
                   exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
                   __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
                   syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
                   do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
                   entry_SYSCALL_64_after_hwframe+0x68/0xd2
 }
 ... key      at: [<ffffffff976dc040>] ppp_register_net_channel.__key.1+0x0/0x20
 ... acquired at:
   mark_lock+0x21c/0x340 kernel/locking/lockdep.c:4628
   __lock_acquire+0xc50/0x1f80 kernel/locking/lockdep.c:5003
   lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
   __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
   _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
   spin_lock include/linux/spinlock.h:351 [inline]
   ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
   ppp_input+0x185/0xa00 drivers/net/ppp/ppp_generic.c:2304
   pppoe_rcv_core+0x112/0x300 drivers/net/ppp/pppoe.c:379
   sk_backlog_rcv include/net/sock.h:1117 [inline]
   __release_sock+0x198/0x4b0 net/core/sock.c:2936
   release_sock+0x5d/0x1c0 net/core/sock.c:3500
   pppoe_sendmsg+0xd1/0x740 drivers/net/ppp/pppoe.c:903
   sock_sendmsg_nosec net/socket.c:718 [inline]
   __sock_sendmsg net/socket.c:730 [inline]
   ____sys_sendmsg+0x5a5/0x8f0 net/socket.c:2514
   ___sys_sendmsg net/socket.c:2568 [inline]
   __sys_sendmmsg+0x3ab/0x730 net/socket.c:2654
   __do_sys_sendmmsg net/socket.c:2683 [inline]
   __se_sys_sendmmsg net/socket.c:2680 [inline]
   __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2680
   do_syscall_x64 arch/x86/entry/common.c:51 [inline]
   do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
   entry_SYSCALL_64_after_hwframe+0x68/0xd2


stack backtrace:
CPU: 1 PID: 7697 Comm: syz.0.805 Not tainted 6.1.112-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 mark_lock_irq+0x836/0xba0 kernel/locking/lockdep.c:4192
 mark_lock+0x21c/0x340 kernel/locking/lockdep.c:4628
 __lock_acquire+0xc50/0x1f80 kernel/locking/lockdep.c:5003
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]
 ppp_input+0x185/0xa00 drivers/net/ppp/ppp_generic.c:2304
 pppoe_rcv_core+0x112/0x300 drivers/net/ppp/pppoe.c:379
 sk_backlog_rcv include/net/sock.h:1117 [inline]
 __release_sock+0x198/0x4b0 net/core/sock.c:2936
 release_sock+0x5d/0x1c0 net/core/sock.c:3500
 pppoe_sendmsg+0xd1/0x740 drivers/net/ppp/pppoe.c:903
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5a5/0x8f0 net/socket.c:2514
 ___sys_sendmsg net/socket.c:2568 [inline]
 __sys_sendmmsg+0x3ab/0x730 net/socket.c:2654
 __do_sys_sendmmsg net/socket.c:2683 [inline]
 __se_sys_sendmmsg net/socket.c:2680 [inline]
 __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2680
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f967c77dff9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f967d5e0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f967c935f80 RCX: 00007f967c77dff9
RDX: 0400000000000026 RSI: 0000000020001cc0 RDI: 0000000000000005
RBP: 00007f967c7f0296 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f967c935f80 R15: 00007ffe44480aa8
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/11 12:19 linux-6.1.y aa4cd140bba5 cd942402 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ppp_input
2024/10/03 21:22 linux-6.1.y aa4cd140bba5 d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ppp_input
2024/09/27 23:12 linux-6.1.y e526b12bf916 440b26ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ppp_input
2024/09/25 02:51 linux-6.1.y e526b12bf916 5643e0e9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in ppp_input
2024/10/16 04:26 linux-6.1.y aa4cd140bba5 bde2d81c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in ppp_input
2024/10/10 00:49 linux-6.1.y aa4cd140bba5 56fb2cb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in ppp_input
2024/10/10 00:48 linux-6.1.y aa4cd140bba5 56fb2cb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in ppp_input
* Struck through repros no longer work on HEAD.