Andrey: It's really hard to tell just what's going on here. On Fri, 12 Apr 2019, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 9a33b369 usb-fuzzer: main usb gadget fuzzer driver > git tree: https://github.com/google/kasan/tree/usb-fuzzer > console output: https://syzkaller.appspot.com/x/log.txt?x=14c4c1af200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15 > dashboard link: https://syzkaller.appspot.com/bug?extid=d919b0f29d7b5a4994b9 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14410dbb200000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f0acd3200000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+d919b0f29d7b5a4994b9@xxxxxxxxxxxxxxxxxxxxxxxxx > > usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > usb-fuzzer-gadget dummy_udc.0: failed to start USB fuzzer: -22 > INFO: task kworker/0:2:532 blocked for more than 143 seconds. > Not tainted 5.1.0-rc4-319354-g9a33b36 #3 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/0:2 D26656 532 2 0x80000000 > Workqueue: usb_hub_wq hub_event > Call Trace: > schedule+0x8f/0x180 kernel/sched/core.c:3562 > usb_kill_urb drivers/usb/core/urb.c:695 [inline] > usb_kill_urb+0x22a/0x2c0 drivers/usb/core/urb.c:687 > usb_start_wait_urb+0x257/0x4d0 drivers/usb/core/message.c:63 > usb_internal_control_msg drivers/usb/core/message.c:101 [inline] > usb_control_msg+0x321/0x4a0 drivers/usb/core/message.c:152 It looks like something is stuck waiting for usb_kill_urb() to finish. But what happened before that? I can't tell from the reproducer source, because it uses a bunch of special stuff you added in your usb-fuzzer tree. Alan Stern
