[79/93] USB: usbfs: only copy the actual data received

[Greg KH]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Greg KH <greg@xxxxxxxxx>

commit d4a4683ca054ed9917dfc9e3ff0f7ecf74ad90d6 upstream.

We need to only copy the data received by the device to userspace, not
the whole kernel buffer, which can contain "stale" data.

Thanks to Marcus Meissner for pointing this out and testing the fix.

Reported-by: Marcus Meissner <meissner@xxxxxxx>
Tested-by: Marcus Meissner <meissner@xxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/usb/core/devio.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1312,9 +1312,9 @@ static int processcompl(struct async *as
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer)
+	if (as->userbuffer && urb->actual_length)
 		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->transfer_buffer_length))
+				 urb->actual_length))
 			goto err_out;
 	if (put_user(as->status, &userurb->status))
 		goto err_out;
@@ -1435,9 +1435,9 @@ static int processcompl_compat(struct as
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer)
+	if (as->userbuffer && urb->actual_length)
 		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->transfer_buffer_length))
+				 urb->actual_length))
 			return -EFAULT;
 	if (put_user(as->status, &userurb->status))
 		return -EFAULT;


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