On Mon, Oct 5, 2020 at 3:59 PM syzbot <syzbot+bf1a360e305ee719e364@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: d3d45f82 Merge tag 'pinctrl-v5.9-2' of git://git.kernel.or.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=15781d8f900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=89ab6a0c48f30b49 > dashboard link: https://syzkaller.appspot.com/bug?extid=bf1a360e305ee719e364 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16cbaa7d900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1364f367900000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+bf1a360e305ee719e364@xxxxxxxxxxxxxxxxxxxxxxxxx > > vhci_hcd: stop threads > vhci_hcd: release socket > vhci_hcd: disconnect device > ================================================================== > BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:71 [inline] > BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline] > BUG: KASAN: null-ptr-deref in refcount_add include/linux/refcount.h:201 [inline] > BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:241 [inline] > BUG: KASAN: null-ptr-deref in get_task_struct include/linux/sched/task.h:104 [inline] > BUG: KASAN: null-ptr-deref in kthread_stop+0x90/0x7e0 kernel/kthread.c:591 > Write of size 4 at addr 000000000000001c by task kworker/u4:5/2519 > > CPU: 1 PID: 2519 Comm: kworker/u4:5 Not tainted 5.9.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: usbip_event event_handler > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x198/0x1fd lib/dump_stack.c:118 > __kasan_report mm/kasan/report.c:517 [inline] > kasan_report.cold+0x5/0x37 mm/kasan/report.c:530 > check_memory_region_inline mm/kasan/generic.c:186 [inline] > check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 > instrument_atomic_write include/linux/instrumented.h:71 [inline] > atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline] > refcount_add include/linux/refcount.h:201 [inline] > refcount_inc include/linux/refcount.h:241 [inline] > get_task_struct include/linux/sched/task.h:104 [inline] > kthread_stop+0x90/0x7e0 kernel/kthread.c:591 > vhci_shutdown_connection+0x170/0x2a0 drivers/usb/usbip/vhci_hcd.c:1015 > event_handler+0x1a5/0x450 drivers/usb/usbip/usbip_event.c:78 > process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 > kthread+0x3b5/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > ================================================================== > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 2519 Comm: kworker/u4:5 Tainted: G B 5.9.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: usbip_event event_handler > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x198/0x1fd lib/dump_stack.c:118 > panic+0x382/0x7fb kernel/panic.c:231 > end_report+0x4d/0x53 mm/kasan/report.c:104 > __kasan_report mm/kasan/report.c:520 [inline] > kasan_report.cold+0xd/0x37 mm/kasan/report.c:530 > check_memory_region_inline mm/kasan/generic.c:186 [inline] > check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 > instrument_atomic_write include/linux/instrumented.h:71 [inline] > atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline] > refcount_add include/linux/refcount.h:201 [inline] > refcount_inc include/linux/refcount.h:241 [inline] > get_task_struct include/linux/sched/task.h:104 [inline] > kthread_stop+0x90/0x7e0 kernel/kthread.c:591 > vhci_shutdown_connection+0x170/0x2a0 drivers/usb/usbip/vhci_hcd.c:1015 > event_handler+0x1a5/0x450 drivers/usb/usbip/usbip_event.c:78 > process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 > kthread+0x3b5/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > Kernel Offset: disabled > Rebooting in 86400 seconds.. Hi Valentina and Shuah, There appears to be a race condition in the USB/IP vhci_hcd shutdown procedure. It happens quite often during fuzzing with syzkaller, and prevents us from going deeper into the USB/IP code. Could you advise us what would be the best fix for this? Thanks in advance!
