| Message ID | 20210806164015.25263-1-mail@anirudhrb.com |
|---|---|
| State | New |
| Headers | show |
| Series | usbip: give back URBs for unsent unlink requests during cleanup | expand |
On Fri, Aug 06, 2021 at 10:46:17PM +0530, Anirudh Rayabharam wrote: > On Fri, Aug 06, 2021 at 06:47:54PM +0200, Greg Kroah-Hartman wrote: > > On Fri, Aug 06, 2021 at 10:10:14PM +0530, 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. Since the code is almost the > > > same, extract it into a new function and call it for both unlink_rx and > > > unlink_tx lists. > > > > > > [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 | 47 ++++++++++++++++++++++++++---------- > > > 1 file changed, 34 insertions(+), 13 deletions(-) > > > > > > diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c > > > index 4ba6bcdaa8e9..45f98aa12895 100644 > > > --- a/drivers/usb/usbip/vhci_hcd.c > > > +++ b/drivers/usb/usbip/vhci_hcd.c > > > @@ -945,7 +945,8 @@ static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) > > > return 0; > > > } > > > > > > -static void vhci_device_unlink_cleanup(struct vhci_device *vdev) > > > +static void __vhci_cleanup_unlink_list(struct vhci_device *vdev, > > > + struct list_head *unlink_list) > > > { > > > struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev); > > > struct usb_hcd *hcd = vhci_hcd_to_hcd(vhci_hcd); > > > @@ -953,23 +954,25 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) > > > struct vhci_unlink *unlink, *tmp; > > > unsigned long flags; > > > > > > + if (unlink_list != &vdev->unlink_tx > > > + && unlink_list != &vdev->unlink_rx) { > > > + pr_err("Invalid list passed to __vhci_cleanup_unlink_list\n"); > > > + BUG(); > > > > Do not allow the system to crash, that is not ok. > > > > > + return; > > > > This call makes no sense as you just rebooted the machine :( > > > > Handle errors properly and recover from them and move on. A single tiny > > driver should not take down the whole system. > > The execution can reach only if there is a developer error and they passed > some random list in `unlink_list`. Why would a developer do that? As that is not the case in the kernel tree, no need to check for it. thanks, greg k-h
diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c index 4ba6bcdaa8e9..45f98aa12895 100644 --- a/drivers/usb/usbip/vhci_hcd.c +++ b/drivers/usb/usbip/vhci_hcd.c @@ -945,7 +945,8 @@ static int vhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status) return 0; } -static void vhci_device_unlink_cleanup(struct vhci_device *vdev) +static void __vhci_cleanup_unlink_list(struct vhci_device *vdev, + struct list_head *unlink_list) { struct vhci_hcd *vhci_hcd = vdev_to_vhci_hcd(vdev); struct usb_hcd *hcd = vhci_hcd_to_hcd(vhci_hcd); @@ -953,23 +954,25 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) struct vhci_unlink *unlink, *tmp; unsigned long flags; + if (unlink_list != &vdev->unlink_tx + && unlink_list != &vdev->unlink_rx) { + pr_err("Invalid list passed to __vhci_cleanup_unlink_list\n"); + BUG(); + return; + } + spin_lock_irqsave(&vhci->lock, flags); spin_lock(&vdev->priv_lock); - list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) { - pr_info("unlink cleanup tx %lu\n", unlink->unlink_seqnum); - list_del(&unlink->list); - kfree(unlink); - } - - while (!list_empty(&vdev->unlink_rx)) { + list_for_each_entry_safe(unlink, tmp, unlink_list, list) { struct urb *urb; - unlink = list_first_entry(&vdev->unlink_rx, struct vhci_unlink, - list); - - /* give back URB of unanswered unlink request */ - pr_info("unlink cleanup rx %lu\n", unlink->unlink_seqnum); + if (unlink_list == &vdev->unlink_tx) + pr_info("unlink cleanup tx %lu\n", + unlink->unlink_seqnum); + else + pr_info("unlink cleanup rx %lu\n", + unlink->unlink_seqnum); urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum); if (!urb) { @@ -1001,6 +1004,24 @@ static void vhci_device_unlink_cleanup(struct vhci_device *vdev) spin_unlock_irqrestore(&vhci->lock, flags); } +static inline void vhci_cleanup_unlink_tx(struct vhci_device *vdev) +{ + __vhci_cleanup_unlink_list(vdev, &vdev->unlink_tx); +} + +static inline void vhci_cleanup_unlink_rx(struct vhci_device *vdev) +{ + __vhci_cleanup_unlink_list(vdev, &vdev->unlink_rx); +} + +static void vhci_device_unlink_cleanup(struct vhci_device *vdev) +{ + /* give back URBs of unsent unlink requests */ + vhci_cleanup_unlink_tx(vdev); + /* give back URBs of unanswered unlink requests */ + vhci_cleanup_unlink_rx(vdev); +} + /* * The important thing is that only one context begins cleanup. * This is why error handling and cleanup become simple.