On Fri, Aug 28, 2020 at 05:52:16AM -0700, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 15bc20c6 Merge tag 'tty-5.9-rc3' of git://git.kernel.org/p.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1052a669900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=978db74cb30aa994 > dashboard link: https://syzkaller.appspot.com/bug?extid=7a7613e5ba9ae7bd15f9 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101c328e900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155eff41900000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+7a7613e5ba9ae7bd15f9@xxxxxxxxxxxxxxxxxxxxxxxxx > > INFO: task syz-executor790:9958 blocked for more than 143 seconds. > Not tainted 5.9.0-rc2-syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz-executor790 state:D stack:28240 pid: 9958 ppid: 6854 flags:0x00004004 > Call Trace: > context_switch kernel/sched/core.c:3778 [inline] > __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 > schedule+0xd0/0x2a0 kernel/sched/core.c:4602 > schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855 > do_wait_for_common kernel/sched/completion.c:85 [inline] > __wait_for_common kernel/sched/completion.c:106 [inline] > wait_for_common kernel/sched/completion.c:117 [inline] > wait_for_completion_timeout+0x15e/0x270 kernel/sched/completion.c:157 > usb_start_wait_urb+0x144/0x2b0 drivers/usb/core/message.c:63 > usb_bulk_msg+0x226/0x550 drivers/usb/core/message.c:254 > do_proc_bulk+0x39b/0x710 drivers/usb/core/devio.c:1231 > proc_bulk drivers/usb/core/devio.c:1268 [inline] > usbdev_do_ioctl drivers/usb/core/devio.c:2542 [inline] > usbdev_ioctl+0x586/0x3360 drivers/usb/core/devio.c:2708 I'm confused about this bug report. Here's the syz reproducer from the link listed above: # https://syzkaller.appspot.com/bug?id=bf172344c5f1d3487a4feff67c3dd30e08d5b635 # See https://goo.gl/kgGztJ for information about syzkaller reproducers. #{"threaded":true,"repeat":true,"procs":6,"sandbox":"none","fault_call":-1,"netdev":true,"close_fds":true} r0 = syz_open_dev$usbfs(&(0x7f0000000040)='/dev/bus/usb/00#/00#\x00', 0x4000000000000071, 0x28081) r1 = socket$inet6(0xa, 0x2, 0x0) r2 = dup(r1) ioctl$PERF_EVENT_IOC_ENABLE(r2, 0x8912, 0x400200) socketpair$unix(0x1, 0x0, 0x0, &(0x7f0000000000)) ioctl$USBDEVFS_CONTROL(r0, 0x8108551b, &(0x7f0000001140)={0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}) ioctl$USBDEVFS_CLEAR_HALT(r0, 0xc0185502, &(0x7f0000000000)={0x1, 0x1}) As far as I can see, the only USB ioctls used in this test are USBDEVFS_CONTROL and USBDEVFS_CLEAR_HALT. Neither of those calls do_proc_bulk() or usb_bulk_msg(), so how did those routines end up in the stack trace? In fact, do_proc_bulk() is called only for USBDEVFS_BULK. But the test doesn't use that ioctl! What's going on? Am I missing part of the test? Alan Stern
