diff options
author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2020-12-20 00:25:53 +0900 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-28 15:44:23 +0100 |
commit | 5e5ff0b4b6bcb4d17b7a26ec8bcfc7dd4651684f (patch) | |
tree | c6edc151e1864da1abc00bae81afde163e629cb7 | |
parent | a390bef7db1f192cc5b588dbcf8ed113406ec130 (diff) | |
download | linux-stable-5e5ff0b4b6bcb4d17b7a26ec8bcfc7dd4651684f.tar.gz linux-stable-5e5ff0b4b6bcb4d17b7a26ec8bcfc7dd4651684f.tar.bz2 linux-stable-5e5ff0b4b6bcb4d17b7a26ec8bcfc7dd4651684f.zip |
USB: cdc-wdm: Fix use after free in service_outstanding_interrupt().
syzbot is reporting UAF at usb_submit_urb() [1], for
service_outstanding_interrupt() is not checking WDM_DISCONNECTING
before calling usb_submit_urb(). Close the race by doing same checks
wdm_read() does upon retry.
Also, while wdm_read() checks WDM_DISCONNECTING with desc->rlock held,
service_interrupt_work() does not hold desc->rlock. Thus, it is possible
that usb_submit_urb() is called from service_outstanding_interrupt() from
service_interrupt_work() after WDM_DISCONNECTING was set and kill_urbs()
from wdm_disconnect() completed. Thus, move kill_urbs() in
wdm_disconnect() to after cancel_work_sync() (which makes sure that
service_interrupt_work() is no longer running) completed.
Although it seems to be safe to dereference desc->intf->dev in
service_outstanding_interrupt() even if WDM_DISCONNECTING was already set
because desc->rlock or cancel_work_sync() prevents wdm_disconnect() from
reaching list_del() before service_outstanding_interrupt() completes,
let's not emit error message if WDM_DISCONNECTING is set by
wdm_disconnect() while usb_submit_urb() is in progress.
[1] https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
Reported-by: syzbot <syzbot+9e04e2df4a32fb661daf@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/620e2ee0-b9a3-dbda-a25b-a93e0ed03ec5@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/usb/class/cdc-wdm.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index 02d0cfd23bb2..508b1c3f8b73 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -465,13 +465,23 @@ static int service_outstanding_interrupt(struct wdm_device *desc) if (!desc->resp_count || !--desc->resp_count) goto out; + if (test_bit(WDM_DISCONNECTING, &desc->flags)) { + rv = -ENODEV; + goto out; + } + if (test_bit(WDM_RESETTING, &desc->flags)) { + rv = -EIO; + goto out; + } + set_bit(WDM_RESPONDING, &desc->flags); spin_unlock_irq(&desc->iuspin); rv = usb_submit_urb(desc->response, GFP_KERNEL); spin_lock_irq(&desc->iuspin); if (rv) { - dev_err(&desc->intf->dev, - "usb_submit_urb failed with result %d\n", rv); + if (!test_bit(WDM_DISCONNECTING, &desc->flags)) + dev_err(&desc->intf->dev, + "usb_submit_urb failed with result %d\n", rv); /* make sure the next notification trigger a submit */ clear_bit(WDM_RESPONDING, &desc->flags); @@ -1027,9 +1037,9 @@ static void wdm_disconnect(struct usb_interface *intf) wake_up_all(&desc->wait); mutex_lock(&desc->rlock); mutex_lock(&desc->wlock); - kill_urbs(desc); cancel_work_sync(&desc->rxwork); cancel_work_sync(&desc->service_outs_intr); + kill_urbs(desc); mutex_unlock(&desc->wlock); mutex_unlock(&desc->rlock); |