This is a note to let you know that I've just added the patch titled
USB: fix use-after-free bug in usb_hcd_unlink_urb()
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From c99197902da284b4b723451c1471c45b18537cde Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 30 Jan 2015 12:58:26 -0500
Subject: USB: fix use-after-free bug in usb_hcd_unlink_urb()
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@xxxxxxxxxxxxxxxxxxx>
Reported-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
Tested-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <greg@xxxxxxxxx>
---
drivers/usb/core/hcd.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 11cee55ae397..45a915ccd71c 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1618,6 +1618,7 @@ 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;
@@ -1629,20 +1630,19 @@ 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;
}
--
2.2.2
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