Patch "USB: devio: Don't corrupt user memory" has been added to the 3.18-stable tree

Patch "USB: devio: Don't corrupt user memory" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    USB: devio: Don't corrupt user memory

to the 3.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-devio-don-t-corrupt-user-memory.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From fa1ed74eb1c233be6131ec92df21ab46499a15b6 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Fri, 22 Sep 2017 23:43:46 +0300
Subject: USB: devio: Don't corrupt user memory

From: Dan Carpenter <dan.carpenter@oracle.com>

commit fa1ed74eb1c233be6131ec92df21ab46499a15b6 upstream.

The user buffer has "uurb->buffer_length" bytes.  If the kernel has more
information than that, we should truncate it instead of writing past
the end of the user's buffer.  I added a WARN_ONCE() to help the user
debug the issue.

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/core/devio.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1413,7 +1413,11 @@ static int proc_do_submiturb(struct usb_
 			totlen += isopkt[u].length;
 		}
 		u *= sizeof(struct usb_iso_packet_descriptor);
-		uurb->buffer_length = totlen;
+		if (totlen <= uurb->buffer_length)
+			uurb->buffer_length = totlen;
+		else
+			WARN_ONCE(1, "uurb->buffer_length is too short %d vs %d",
+				  totlen, uurb->buffer_length);
 		break;
 
 	default:


Patches currently in stable-queue which might be from dan.carpenter@oracle.com are

queue-3.18/usb-devio-don-t-corrupt-user-memory.patch