diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2015-01-30 12:58:26 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-06 14:43:30 -0800 |
| commit | 5b8e6d47e5af9081320ac50f354f6ff609e32105 (patch) | |
| tree | ca175ceb9a0b4e0514a7a50c308351656fc8f221 | |
| parent | d6fe76a0c708d47b44298a5d5369e906c616ebb0 (diff) | |
USB: fix use-after-free bug in usb_hcd_unlink_urb()
commit c99197902da284b4b723451c1471c45b18537cde upstream.
The usb_hcd_unlink_urb() routine in hcd.c contains two possible
use-after-free errors. The dev_dbg() statement at the end of the
routine dereferences urb and urb->dev even though both structures may
have been deallocated.
This patch fixes the problem by storing urb->dev in a local variable
(avoiding the dereference of urb) and moving the dev_dbg() up before
the usb_put_dev() call.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/core/hcd.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index ef6ec13b6ae5..ee6c5562d296 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1617,6 +1617,7 @@ static int unlink1(struct usb_hcd *hcd, struct urb *urb, int status) int usb_hcd_unlink_urb (struct urb *urb, int status) { struct usb_hcd *hcd; + struct usb_device *udev = urb->dev; int retval = -EIDRM; unsigned long flags; @@ -1628,20 +1629,19 @@ int usb_hcd_unlink_urb (struct urb *urb, int status) spin_lock_irqsave(&hcd_urb_unlink_lock, flags); if (atomic_read(&urb->use_count) > 0) { retval = 0; - usb_get_dev(urb->dev); + usb_get_dev(udev); } spin_unlock_irqrestore(&hcd_urb_unlink_lock, flags); if (retval == 0) { hcd = bus_to_hcd(urb->dev->bus); retval = unlink1(hcd, urb, status); - usb_put_dev(urb->dev); + if (retval == 0) + retval = -EINPROGRESS; + else if (retval != -EIDRM && retval != -EBUSY) + dev_dbg(&udev->dev, "hcd_unlink_urb %p fail %d\n", + urb, retval); + usb_put_dev(udev); } - - if (retval == 0) - retval = -EINPROGRESS; - else if (retval != -EIDRM && retval != -EBUSY) - dev_dbg(&urb->dev->dev, "hcd_unlink_urb %p fail %d\n", - urb, retval); return retval; } |