Commit 68a2bed1 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

USB: fix urb-poison imbalance 



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@rowland.harvard.edu>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 69a3d212

drivers/usb/core/urb.c

+4 −1
Original line number Diff line number Diff line
@@ -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);

}

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