[syzbot] [usb?] INFO: task hung in usbatm_usb_disconnect (2)

[syzbot] [usb?] INFO: task hung in usbatm_usb_disconnect (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14e92005580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca2c9f85bd8b5e46516
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=158a64c9580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12e92005580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/daf497619736/disk-50d05c7c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/748fbd82f647/vmlinux-50d05c7c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e61c59099d07/bzImage-50d05c7c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca2c9f85bd8b5e46516@syzkaller.appspotmail.com

INFO: task kworker/1:1:30 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1     state:D stack:23656 pid:30    tgid:30    ppid:2      task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x17db/0x58f0 kernel/sched/core.c:7276
 __schedule_loop kernel/sched/core.c:7353 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7368
 schedule_timeout+0xc0/0x2c0 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2ca/0x5e0 kernel/sched/completion.c:153
 usbatm_usb_disconnect+0x111/0x620 drivers/usb/atm/usbatm.c:1227
 usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:461
 device_remove drivers/base/dd.c:618 [inline]
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372
 bus_remove_device+0x444/0x560 drivers/base/bus.c:664
 device_del+0x524/0x8f0 drivers/base/core.c:3965
 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478
 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2350
 hub_port_connect drivers/usb/core/hub.c:5420 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
 port_event drivers/usb/core/hub.c:5884 [inline]
 hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5966
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task kworker/0:3:5785 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:3     state:D stack:22304 pid:5785  tgid:5785  ppid:2      task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5526 [inline]
 __schedule+0x17db/0x58f0 kernel/sched/core.c:7276
 __schedule_loop kernel/sched/core.c:7353 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7368
 schedule_timeout+0xc0/0x2c0 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2ca/0x5e0 kernel/sched/completion.c:153
 usbatm_usb_disconnect+0x111/0x620 drivers/usb/atm/usbatm.c:1227
 usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:461
 device_remove drivers/base/dd.c:618 [inline]
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372
 bus_remove_device+0x444/0x560 drivers/base/bus.c:664
 device_del+0x524/0x8f0 drivers/base/core.c:3965
 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478
 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2350
 hub_port_connect drivers/usb/core/hub.c:5420 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5720 [inline]
 port_event drivers/usb/core/hub.c:5884 [inline]
 hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5966
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
locks held by pr/ttyS0/16: 1, last CPU#0:
 #0: ffffffff8ec364b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
 #0: ffffffff8ec364b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
 #0: ffffffff8ec364b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
locks held by kworker/1:1/30: 5, on CPU#1:
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90000a57c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90000a57c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90000a57c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90000a57c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff88802a8311d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #2: ffff88802a8311d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
 #3: ffff88802a7c01d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #3: ffff88802a7c01d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2341
 #4: ffff8880262161a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff8880262161a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
 #4: ffff8880262161a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369
locks held by khungtaskd/32: 1, last CPU#0:
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by kworker/u8:7/159: 4, last CPU#1:
 #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90002e5fc40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90002e5fc40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90002e5fc40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90002e5fc40 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff888058bf4258 (&devlink->lock_key#6){+.+.}-{4:4}, at: nsim_dev_trap_report_work+0x57/0xb40 drivers/net/netdevsim/dev.c:834
 #3: ffff8880b873bb20 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:677
locks held by kworker/1:2/1219: 2, last CPU#1:
 #0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801b069d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc900055f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc900055f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc900055f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc900055f7c40 ((work_completion)(&(&gc_work->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by getty/5374: 2, on CPU#1:
 #0: ffff8880362860a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by udevd/5666: 4, on CPU#1:
 #0: ffff88802be1ebd8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0 fs/seq_file.c:183
 #1: ffff88807a98b080 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165
 #2: ffff8880783b7788 (kn->active#27){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff8880783b7788 (kn->active#27){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:166
 #3: ffff8880798bb1d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline]
 #3: ffff8880798bb1d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0 drivers/usb/core/sysfs.c:142
locks held by udevd/5682: 4, on CPU#1:
 #0: ffff88807c253ab8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0 fs/seq_file.c:183
 #1: ffff88807a959080 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5d/0x420 fs/kernfs/file.c:165
 #2: ffff8880764c8878 (kn->active#32){++++}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff8880764c8878 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420 fs/kernfs/file.c:166
 #3: ffff88802a7c01d8 (&dev->mutex){....}-{4:4}, at: device_lock_interruptible include/linux/device.h:1109 [inline]
 #3: ffff88802a7c01d8 (&dev->mutex){....}-{4:4}, at: serial_show+0x26/0xa0 drivers/usb/core/sysfs.c:143
locks held by syz-executor/5784: 1, last CPU#1:
 #0: ffffffff8ed5c8a0 (rcu_read_lock){....}-{1:3}, at: hrtimer_run_softirq+0x71/0x2e0 kernel/time/hrtimer.c:2138
locks held by kworker/0:3/5785: 5, on CPU#0:
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000337fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000337fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000337fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000337fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff88802a78c1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #2: ffff88802a78c1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
 #3: ffff8880798bb1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #3: ffff8880798bb1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0 drivers/usb/core/hub.c:2341
 #4: ffff888034dc71a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff888034dc71a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
 #4: ffff888034dc71a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369
locks held by udevd/5795: 1, last CPU#0:
 #0: ffffffff8f4f0b78 (tomoyo_ss){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
 #0: ffffffff8f4f0b78 (tomoyo_ss){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:305 [inline]
 #0: ffffffff8f4f0b78 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_read_lock security/tomoyo/common.h:1112 [inline]
 #0: ffffffff8f4f0b78 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_perm+0x251/0x560 security/tomoyo/file.c:826
locks held by kworker/1:6/5912: 5, on CPU#1:
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000302fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000302fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000302fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000302fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff88802a8671d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #2: ffff88802a8671d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
 #3: ffff88802fc3c1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #3: ffff88802fc3c1d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
 #4: ffff88807c5561a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff88807c5561a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
locks held by kworker/1:7/6008: 3, on CPU#1:
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888022ae4940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90002fafc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90002fafc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90002fafc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90002fafc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff88802a6e61d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #2: ffff88802a6e61d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
locks held by speedtch/6052: 1, on CPU#0:
 #0: ffffffff8ebf7d08 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xfc/0x2c0 kernel/umh.c:212

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1219 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_power_efficient gc_worker
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63
Code: f5 48 8b 74 24 20 48 c7 c7 00 9b 6d 8c e8 88 ac 42 f5 e8 23 ab 4d f5 eb ae 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 89 fe 48 c7 c7 80 9a 6d 8c e9 0d ff ff ff cc cc cc
RSP: 0018:ffffc900055f7938 EFLAGS: 00000046
RAX: 8000000000000000 RBX: ffffffff8a0040de RCX: ffff888029898000
RDX: 0000000000000000 RSI: 0000000000000200 RDI: ffffffff8e4e3f89
RBP: ffffc900055f7ad0 R08: ffffffff8a010014 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff20f4570 R12: dffffc0000000000
R13: ffffffff818f9aba R14: 0000000000000200 R15: 0000000000000e5a
FS:  0000000000000000(0000) GS:ffff888124dd2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000579c31ec CR3: 00000000727d2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lockdep_hardirqs_off+0x8e/0xd0 kernel/locking/lockdep.c:4539
 trace_hardirqs_off+0x12/0x40 kernel/trace/trace_preemptirq.c:104
 seqcount_lockdep_reader_access+0x6e/0x100 include/linux/seqlock.h:72
 nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:343 [inline]
 gc_worker+0x31b/0x1890 net/netfilter/nf_conntrack_core.c:1534
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

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#syz dup: exact-subject-of-another-report

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Subject: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
Author: valigurasm@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
master

Forwarded: Re: [syzbot] [usb?] INFO: task hung in usbatm_usb_disconnect (2)

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Subject: Re: [syzbot] [usb?] INFO: task hung in usbatm_usb_disconnect (2)
Author: valigurasm@gmail.com

#syz test: upstream master

On Thu, 24 Sept 2026, 01:01 syzbot, <
syzbot+9ca2c9f85bd8b5e46516@syzkaller.appspotmail.com> wrote:

> Hello,
>
> syzbot tried to test the proposed patch but the build/boot failed:
>
> lost connection to test machine
>
>
>
> Warning: Permanently added '10.128.1.106' (ED25519) to the list of known
> hosts.
> 2026/09/23 21:58:53 parsed 1 programs
> 2026/09/23 21:58:53 serving rpc on tcp://36741
> [  108.303160][  T923] cfg80211: failed to load regulatory.db
> [  112.594660][ T5628] cgroup: Unknown subsys name 'net'
> [  112.732732][ T5628] cgroup: Unknown subsys name 'cpuset'
> [  112.746517][ T5628] cgroup: Unknown subsys name 'rlimit'
> Setting up swapspace version 1, size = 127995904 bytes
> [  114.653895][ T5628] Adding 124996k swap on ./swap-file.  Priority:0
> extents:1 across:124996k
> [  118.241459][ T5649] soft_limit_in_bytes is deprecated and will be
> removed. Writing any value to this file has no effect. Please report your
> usecase to linux-mm@kvack.org if you depend on this functionality.
> [  118.312791][ T5649] ebtables: xtables 32bit compat interface no longer
> supported in namespaces and will be removed soon.
> [  118.342551][ T5649] arp_tables: xtables 32bit compat interface no
> longer supported in namespaces and will be removed soon.
> [  118.935095][ T1161] wlan0: Created IBSS using preconfigured BSSID
> 50:50:50:50:50:50
> [  118.935132][ T1161] wlan0: Creating new IBSS network, BSSID
> 50:50:50:50:50:50
> [  119.314186][   T60] wlan1: Created IBSS using preconfigured BSSID
> 50:50:50:50:50:50
> [  119.314208][   T60] wlan1: Creating new IBSS network, BSSID
> 50:50:50:50:50:50
> [  119.514008][ T5659] ip_tables: xtables 32bit compat interface no longer
> supported in namespaces and will be removed soon.
> [  119.514671][ T5659] ip6_tables: xtables 32bit compat interface no
> longer supported in namespaces and will be removed soon.
> [  120.499036][ T5685] Bluetooth: hci0: unexpected cc 0x0c03 length: 249 >
> 1
> [  120.504897][ T5685] Bluetooth: hci0: unexpected cc 0x1003 length: 249 >
> 9
> [  120.505931][ T5685] Bluetooth: hci0: unexpected cc 0x1001 length: 249 >
> 9
> [  120.507278][ T5685] Bluetooth: hci0: unexpected cc 0x0c23 length: 249 >
> 4
> [  120.541791][ T5685] Bluetooth: hci0: unexpected cc 0x0c38 length: 249 >
> 2
> [  122.840866][ T5680] bridge0: port 1(bridge_slave_0) entered blocking
> state
> [  122.841743][ T5680] bridge0: port 1(bridge_slave_0) entered disabled
> state
> [  122.842082][ T5680] bridge_slave_0: entered allmulticast mode
> [  122.862531][ T5680] bridge_slave_0: entered promiscuous mode
> [  122.889547][ T5680] bridge0: port 2(bridge_slave_1) entered blocking
> state
> [  122.889656][ T5680] bridge0: port 2(bridge_slave_1) entered disabled
> state
> [  122.889794][ T5680] bridge_slave_1: entered allmulticast mode
> [  122.891937][ T5680] bridge_slave_1: entered promiscuous mode
> [  122.984739][ T5680] bond0: (slave bond_slave_0): Enslaving as an active
> interface with an up link
> [  123.001661][ T5680] bond0: (slave bond_slave_1): Enslaving as an active
> interface with an up link
> [  123.051936][ T5680] team0: Port device team_slave_0 added
> [  123.055615][ T5680] team0: Port device team_slave_1 added
> [  123.112267][ T5680] batman_adv: batadv0: Adding interface:
> batadv_slave_0
> [  123.112288][ T5680] batman_adv: batadv0: The MTU of interface
> batadv_slave_0 is too small (1500) to handle the transport of batman-adv
> packets. Packets going over this interface will be fragmented on layer2
> which could impact the performance. Setting the MTU to 1532 would solve the
> problem.
> [  123.112327][ T5680] batman_adv: batadv0: Not using interface
> batadv_slave_0 (retrying later): interface not active
> [  123.116516][ T5680] batman_adv: batadv0: Adding interface:
> batadv_slave_1
> [  123.116534][ T5680] batman_adv: batadv0: The MTU of interface
> batadv_slave_1 is too small (1500) to handle the transport of batman-adv
> packets. Packets going over this interface will be fragmented on layer2
> which could impact the performance. Setting the MTU to 1532 would solve the
> problem.
> [  123.116558][ T5680] batman_adv: batadv0: Not using interface
> batadv_slave_1 (retrying later): interface not active
> [  123.261249][ T5680] hsr_slave_0: entered promiscuous mode
> [  123.262263][ T5680] hsr_slave_1: entered promiscuous mode
> [  123.471857][ T5680] netdevsim netdevsim8 netdevsim0: renamed from eth0
> [  123.487856][ T5680] 8021q: adding VLAN 0 to HW filter on device
> netdevsim0
> [  123.489120][ T5680] netdevsim netdevsim8 netdevsim1: renamed from eth1
> [  123.493156][ T5680] 8021q: adding VLAN 0 to HW filter on device
> netdevsim1
> [  123.494176][ T5680] netdevsim netdevsim8 netdevsim2: renamed from eth2
> [  123.504829][ T5680] 8021q: adding VLAN 0 to HW filter on device
> netdevsim2
> [  123.507973][ T5680] netdevsim netdevsim8 netdevsim3: renamed from eth3
> [  123.548418][ T5680] 8021q: adding VLAN 0 to HW filter on device
> netdevsim3
> [  123.652099][ T5680] 8021q: adding VLAN 0 to HW filter on device bond0
> [  123.685093][ T5680] 8021q: adding VLAN 0 to HW filter on device team0
> [  123.702139][   T60] bridge0: port 1(bridge_slave_0) entered blocking
> state
> [  123.702279][   T60] bridge0: port 1(bridge_slave_0) entered forwarding
> state
> [  123.730774][   T78] bridge0: port 2(bridge_slave_1) entered blocking
> state
> [  123.730885][   T78] bridge0: port 2(bridge_slave_1) entered forwarding
> state
> [  124.170694][ T5680] 8021q: adding VLAN 0 to HW filter on device batadv0
> [  124.430316][ T5680] veth0_vlan: entered promiscuous mode
> [  124.447342][ T5680] veth1_vlan: entered promiscuous mode
> [  124.488229][ T5680] veth0_macvtap: entered promiscuous mode
> [  124.492929][ T5680] veth1_macvtap: entered promiscuous mode
> [  124.527631][ T5680] batman_adv: batadv0: Interface activated:
> batadv_slave_0
> [  124.540115][ T5680] batman_adv: batadv0: Interface activated:
> batadv_slave_1
> execution of simple program fails: NOTFAIL: arptable checkpoint:
> getsockopt(ARPT_SO_GET_ENTRIES) failed. table=filter (errno 22: Invalid
> argument).
> [  124.647568][ T1161] netdevsim netdevsim8 netdevsim0: set [1, 0] type 2
> family 0 port 6081 - 0
> [  124.647619][ T1161] netdevsim netdevsim8 netdevsim1: set [1, 0] type 2
> family 0 port 6081 - 0
> [  124.647655][ T1161] netdevsim netdevsim8 netdevsim2: set [1, 0] type 2
> family 0 port 6081 - 0
> [  124.647690][ T1161] netdevsim netdevsim8 netdevsim3: set [1, 0] type 2
> family 0 port 6081 - 0
> [  124.806492][ T1161] netdevsim netdevsim8 netdevsim3 (unregistering):
> unset [1, 0] type 2 family 0 port 6081 - 0
> [  124.903314][ T1161] netdevsim netdevsim8 netdevsim2 (unregistering):
> unset [1, 0] type 2 family 0 port 6081 - 0
> [  124.980877][ T1161] netdevsim netdevsim8 netdevsim1 (unregistering):
> unset [1, 0] type 2 family 0 port 6081 - 0
> [  125.116872][ T1161] netdevsim netdevsim8 netdevsim0 (unregistering):
> unset [1, 0] type 2 family 0 port 6081 - 0
> [  125.883310][ T1161] bridge_slave_1: left allmulticast mode
> [  125.883361][ T1161] bridge_slave_1: left promiscuous mode
> [  125.884401][ T1161] bridge0: port 2(bridge_slave_1) entered disabled
> state
> [  125.920237][ T1161] bridge_slave_0: left allmulticast mode
> [  125.920268][ T1161] bridge_slave_0: left promiscuous mode
> [  125.920607][ T1161] bridge0: port 1(bridge_slave_0) entered disabled
> state
> [  126.095488][ T1161] bond0 (unregistering): (slave bond_slave_0):
> Releasing backup interface
> [  126.110922][ T1161] bond0 (unregistering): (slave bond_slave_1):
> Releasing backup interface
> [  126.112236][ T1161] bond0 (unregistering): Released all slaves
> [  126.223248][ T1161] hsr_slave_0: left promiscuous mode
> [  126.226835][ T1161] hsr_slave_1: left promiscuous mode
> [  126.233387][ T1161] batman_adv: batadv0: Interface deactivated:
> batadv_slave_0
> [  126.233431][ T1161] batman_adv: batadv0: Removing interface:
> batadv_slave_0
> [  126.241512][ T1161] batman_adv: batadv0: Interface deactivated:
> batadv_slave_1
> [  126.241585][ T1161] batman_adv: batadv0: Removing interface:
> batadv_slave_1
> [  126.286396][ T1161] veth1_macvtap: left promiscuous mode
> [  126.286461][ T1161] veth0_macvtap: left promiscuous mode
> [  126.286648][ T1161] veth1_vlan: left promiscuous mode
> [  126.286760][ T1161] veth0_vlan: left promiscuous mode
> [  126.654559][ T1161] team0 (unregistering): Port device team_slave_1
> removed
> [  126.682089][ T1161] team0 (unregistering): Port device team_slave_0
> removed
> [  126.875676][ T5279] 8021q: adding VLAN 0 to HW filter on device eth1
> [  127.409335][ T5279] 8021q: adding VLAN 0 to HW filter on device eth2
> [  127.993497][ T5279] 8021q: adding VLAN 0 to HW filter on device eth3
> [  128.438182][ T5279] 8021q: adding VLAN 0 to HW filter on device eth4
> [  139.019729][ T1313] ieee802154 phy0 wpan0: encryption failed: -22
> [  139.019831][ T1313] ieee802154 phy1 wpan1: encryption failed: -22
>
>
> syzkaller build log:
> go env (err=<nil>)
> AR='ar'
> CC='gcc'
> CGO_CFLAGS='-O2 -g'
> CGO_CPPFLAGS=''
> CGO_CXXFLAGS='-O2 -g'
> CGO_ENABLED='1'
> CGO_FFLAGS='-O2 -g'
> CGO_LDFLAGS='-O2 -g'
> CXX='g++'
> GCCGO='gccgo'
> GO111MODULE='auto'
> GOAMD64='v1'
> GOARCH='amd64'
> GOAUTH='netrc'
> GOBIN=''
> GOCACHE='/syzkaller/.cache/go-build'
> GOCACHEPROG=''
> GODEBUG=''
> GOENV='/syzkaller/.config/go/env'
> GOEXE=''
> GOEXPERIMENT=''
> GOFIPS140='off'
> GOFLAGS=''
> GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0
> -ffile-prefix-map=/tmp/go-build3081947690=/tmp/go-build
> -gno-record-gcc-switches'
> GOHOSTARCH='amd64'
> GOHOSTOS='linux'
> GOINSECURE=''
> GOMOD='/syzkaller/jobs-2/linux/gopath/src/
> github.com/google/syzkaller/go.mod'
> GOMODCACHE='/syzkaller/jobs-2/linux/gopath/pkg/mod'
> GONOPROXY=''
> GONOSUMDB=''
> GOOS='linux'
> GOPATH='/syzkaller/jobs-2/linux/gopath'
> GOPRIVATE=''
> GOPROXY='https://proxy.golang.org,direct'
> GOROOT='/usr/local/go'
> GOSUMDB='sum.golang.org'
> GOTELEMETRY='local'
> GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
> GOTMPDIR=''
> GOTOOLCHAIN='auto'
> GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
> GOVCS=''
> GOVERSION='go1.26.0'
> GOWORK=''
> PKG_CONFIG='pkg-config'
>
> git status (err=<nil>)
> HEAD detached at 853b104bb45
> nothing to commit, working tree clean
>
>
> tput: No value for $TERM and no -T specified
> tput: No value for $TERM and no -T specified
> Makefile:31: run command via tools/syz-env for best compatibility, see:
> Makefile:32:
> https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
> go list -f '{{.Stale}}' -ldflags="-s -w -X
> github.com/google/syzkaller/prog.GitRevision=853b104bb454141a5b0fc0e4218ec78e9f34ffb1
> -X github.com/google/syzkaller/prog.gitRevisionDate=20260918-062331"
> ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X
> github.com/google/syzkaller/prog.GitRevision=853b104bb454141a5b0fc0e4218ec78e9f34ffb1
> -X github.com/google/syzkaller/prog.gitRevisionDate=20260918-062331"
> ./sys/syz-sysgen
> make .descriptions
> tput: No value for $TERM and no -T specified
> tput: No value for $TERM and no -T specified
> Makefile:31: run command via tools/syz-env for best compatibility, see:
> Makefile:32:
> https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
> bin/syz-sysgen
> <https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-envbin/syz-sysgen>
> touch .descriptions
> GOOS=linux GOARCH=amd64 go build -ldflags="-s -w -X
> github.com/google/syzkaller/prog.GitRevision=853b104bb454141a5b0fc0e4218ec78e9f34ffb1
> -X github.com/google/syzkaller/prog.gitRevisionDate=20260918-062331"  -o
> ./bin/linux_amd64/syz-execprog
> github.com/google/syzkaller/tools/syz-execprog
> mkdir -p ./bin/linux_386
> x86_64-linux-gnu-g++ -o ./bin/linux_386/syz-executor executor/executor.cc \
>         -m32 -O2 -pthread -Wall -Werror -Wparentheses
> -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow
> -Wno-array-bounds -Wno-format-overflow -Wno-unused-but-set-variable
> -Wno-unused-command-line-argument -static-pie -std=c++17 -I.
> -Iexecutor/_include   -DGOOS_linux=1 -DGOARCH_386=1 \
>         -DHOSTGOOS_linux=1
> -DGIT_REVISION=\"853b104bb454141a5b0fc0e4218ec78e9f34ffb1\"
> /usr/bin/ld: /tmp/cctVKtvW.o: in function `Connection::Connect(char
> const*, char const*)':
> executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x145):
> warning: Using 'gethostbyname' in statically linked applications requires
> at runtime the shared libraries from the glibc version used for linking
> ./tools/check-syzos.sh 2>/dev/null
> [INFO] Unsupported architecture '386', skipping check.
>
>
>
> Tested on:
>
> commit:         fe2ec837 Merge tag 'hid-for-linus-2026092202' of git:/..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=9d4242cb1c54cdf7
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=9ca2c9f85bd8b5e46516
> compiler:       Debian clang version 22.1.8
> (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> userspace arch: i386
> patch:
> https://syzkaller.appspot.com/x/patch.diff?x=11123405580000
>
>

Forwarded: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
Author: tristmd@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

>From fa9693d02a6d2e2fda72504085400c761d5eec1f Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Sat, 18 Apr 2026 13:39:03 +0000
Subject: [PATCH] hfsplus: zero-initialize buffer in hfs_bnode_read

hfs_bnode_read() can return early without initializing the output
buffer when the offset is invalid or the requested length is
corrected to zero by check_and_correct_requested_length().  Callers
such as hfs_bnode_read_u16() pass stack-allocated buffers and use the
result unconditionally, leading to KMSAN uninit-value reports.

Rather than initializing at each individual call site, zero the buffer
at the start of hfs_bnode_read() before any validation checks.  This
ensures the buffer is always in a known state regardless of which
early-return path is taken.

Reported-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com
Tested-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=217eb327242d08197efb
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 fs/hfsplus/bnode.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/hfsplus/bnode.c b/fs/hfsplus/bnode.c
index f8b5a8ae58ff5..14d1af2c7ba93 100644
--- a/fs/hfsplus/bnode.c
+++ b/fs/hfsplus/bnode.c
@@ -25,6 +25,8 @@ void hfs_bnode_read(struct hfs_bnode *node, void *buf, u32 off, u32 len)
 	struct page **pagep;
 	u32 l;
 
+	memset(buf, 0, len);
+
 	if (!is_bnode_offset_valid(node, off))
 		return;
 
-- 
2.47.3

Forwarded: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
Author: tristmd@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

>From 9c3f65e66c3a938b75d165bec0686e05db473070 Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Thu, 30 Apr 2026 23:57:44 +0000
Subject: [PATCH] jffs2: fix GC thread BUG_ON during reconfigure via fspick

jffs2_do_remount_fs() uses fc->sb_flags to decide whether to start
the garbage collection thread.  However, when called via fspick(2)
followed by fsconfig(FSCONFIG_CMD_RECONFIGURE), fc->sb_flags does
not reflect the current mount state -- it only contains flags being
explicitly changed (as indicated by fc->sb_flags_mask).

When fspick() is called with flags=0 on a read-only mount,
fc->sb_flags has SB_RDONLY clear (since SB_RDONLY is not in
sb_flags_mask).  This causes jffs2_start_garbage_collect_thread()
to be called even though the filesystem remains read-only.  On the
second reconfigure, BUG_ON(c->gc_task) fires because the thread
from the first call is still running.

Fix this by computing the effective read-only state using both
fc->sb_flags and fc->sb_flags_mask.  Also unconditionally call
jffs2_stop_garbage_collect_thread() before potentially restarting
it, which is safe when gc_task is NULL and prevents the BUG_ON.

Reported-by: syzbot+61a9d95630970eece39d@syzkaller.appspotmail.com
Fixes: ec10a24f10c8f ("vfs: Convert jffs2 to use the new mount API")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 fs/jffs2/fs.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 6ada8369a7622..33574312b7abe 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -396,28 +396,28 @@ void jffs2_dirty_inode(struct inode *inode, int flags)
 int jffs2_do_remount_fs(struct super_block *sb, struct fs_context *fc)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
+	bool new_ro;
 
 	if (c->flags & JFFS2_SB_FLAG_RO && !sb_rdonly(sb))
 		return -EROFS;
 
-	/* We stop if it was running, then restart if it needs to.
-	   This also catches the case where it was stopped and this
-	   is just a remount to restart it.
-	   Flush the writebuffer, if necessary, else we loose it */
+	new_ro = (fc->sb_flags_mask & SB_RDONLY) ?
+		 (fc->sb_flags & SB_RDONLY) : sb_rdonly(sb);
+
+	jffs2_stop_garbage_collect_thread(c);
+
 	if (!sb_rdonly(sb)) {
-		jffs2_stop_garbage_collect_thread(c);
 		mutex_lock(&c->alloc_sem);
 		jffs2_flush_wbuf_pad(c);
 		mutex_unlock(&c->alloc_sem);
 	}
 
-	if (!(fc->sb_flags & SB_RDONLY))
+	if (!new_ro)
 		jffs2_start_garbage_collect_thread(c);
 
 	fc->sb_flags |= SB_NOATIME;
 	return 0;
 }
-
 /* jffs2_new_inode: allocate a new inode and inocache, add it to the hash,
    fill in the raw_inode while you're at it. */
 struct inode *jffs2_new_inode (struct inode *dir_i, umode_t mode, struct jffs2_raw_inode *ri)
-- 
2.47.3