The calls to usb_poison_urb and usb_unpoison_urb are expected to be
balanced. However, if an urb that has not yet been submitted is
poisoned, its reject counter will not be increased as its ep-field is
NULL. A consecutive call to unpoison will thus in fact poison the urb
as its reject counter will be decremented to a negative value,
effectively preventing the urb from being submitted.
Note that there are currently no in-kernel drivers affected by this.
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
---
drivers/usb/core/urb.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index e0d9d94..16927fa 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -683,10 +683,13 @@ EXPORT_SYMBOL_GPL(usb_kill_urb);
void usb_poison_urb(struct urb *urb)
{
might_sleep();
- if (!(urb && urb->dev && urb->ep))
+ if (!urb)
return;
atomic_inc(&urb->reject);
+ if (!urb->dev || !urb->ep)
+ return;
+
usb_hcd_unlink_urb(urb, -ENOENT);
wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);
}
--
1.8.1.5
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