| Message ID | 20210820190122.16379-1-mail@anirudhrb.com |
|---|---|
| Headers | show |
| Series | Fix syzkaller bug: hung task in hub_port_init | expand |
On 8/20/21 1:01 PM, Anirudh Rayabharam wrote: > In vhci_device_unlink_cleanup(), the URBs for unsent unlink requests are > not given back. This sometimes causes usb_kill_urb to wait indefinitely > for that urb to be given back. syzbot has reported a hung task issue [1] > for this. > > To fix this, give back the urbs corresponding to unsent unlink requests > (unlink_tx list) similar to how urbs corresponding to unanswered unlink > requests (unlink_rx list) are given back. > > [1]: https://syzkaller.appspot.com/bug?id=08f12df95ae7da69814e64eb5515d5a85ed06b76 > > Reported-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com > Tested-by: syzbot+74d6ef051d3d2eacf428@syzkaller.appspotmail.com > Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com> > --- > drivers/usb/usbip/vhci_hcd.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c > index 4ba6bcdaa8e9..190bd3d1c1f0 100644 > --- a/drivers/usb/usbip/vhci_hcd.c > +++ b/drivers/usb/usbip/vhci_hcd.c > @@ -957,8 +957,32 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) > spin_lock(&vdev->priv_lock); > > list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) { > + struct urb *urb; > + > + /* give back urb of unsent unlink request */ > pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum); > + > + urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum); > + if (!urb) { > + list_del(&unlink->list); > + kfree(unlink); > + continue; > + } > + > + urb->status = -ENODEV; > + > + usb_hcd_unlink_urb_from_ep(hcd, urb); > + > list_del(&unlink->list); > + > + spin_unlock(&vdev->priv_lock); > + spin_unlock_irqrestore(&vhci->lock, flags); > + > + usb_hcd_giveback_urb(hcd, urb, urb->status); > + > + spin_lock_irqsave(&vhci->lock, flags); > + spin_lock(&vdev->priv_lock); > + > kfree(unlink); > } > > Looks good. Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> thanks, -- Shuah
This series fixes the hung task bug in hub_port_init reported by syzkaller at: https://syzkaller.appspot.com/bug?id=08f12df95ae7da69814e64eb5515d5a85ed06b76 Stack: INFO: task kworker/0:0:5 blocked for more than 143 seconds. Not tainted 5.13.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:27392 pid: 5 ppid: 2 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:4339 [inline] __schedule+0x916/0x23e0 kernel/sched/core.c:5147 schedule+0xcf/0x270 kernel/sched/core.c:5226 usb_kill_urb.part.0+0x19c/0x220 drivers/usb/core/urb.c:711 usb_kill_urb+0x81/0xa0 drivers/usb/core/urb.c:706 usb_start_wait_urb+0x24a/0x4c0 drivers/usb/core/message.c:64 usb_internal_control_msg drivers/usb/core/message.c:102 [inline] usb_control_msg+0x31c/0x4a0 drivers/usb/core/message.c:153 hub_port_init+0x82e/0x2db0 drivers/usb/core/hub.c:4759 hub_port_connect drivers/usb/core/hub.c:5210 [inline] hub_port_connect_change drivers/usb/core/hub.c:5418 [inline] port_event drivers/usb/core/hub.c:5564 [inline] hub_event+0x2190/0x4330 drivers/usb/core/hub.c:5646 process_one_work+0x98d/0x1600 kernel/workqueue.c:2276 worker_thread+0x64c/0x1120 kernel/workqueue.c:2422 kthread+0x3b1/0x4a0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 The first patch in the series fixes the issue and the second patch does some refactoring to avoid duplicate code. Changes in v4: - Got rid of the log messages as suggested by Shuah. Changes in v3: - Split the patch into two patches - Remove the convenience wrappers as suggested by Shuah - Remove the WARN as suggested by Greg Link: https://lore.kernel.org/lkml/20210813182508.28127-1-mail@anirudhrb.com/ Changes in v2: Use WARN_ON() instead of BUG() when unlink_list is neither unlink_tx nor unlink_rx. Link: https://lore.kernel.org/lkml/20210806181335.2078-1-mail@anirudhrb.com/ v1: https://lore.kernel.org/lkml/20210806164015.25263-1-mail@anirudhrb.com/ Anirudh Rayabharam (2): usbip: give back URBs for unsent unlink requests during cleanup usbip: clean up code in vhci_device_unlink_cleanup drivers/usb/usbip/vhci_hcd.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-)