[SECURITY] CAN-2004-0075 (was: Re: [SECURITY] CAN-2004-0109 isofs fix.)

[Marc-Christian Petersen <m.c.p@kernel.linux-systeme.com>]

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On Wednesday 14 April 2004 19:11, Dave Jones wrote:

Hi,

> Merged in 2.4, and various vendor kernels today..

Okay, now while we are at fixing security holes, is there any chance we 
can _finally_ get the attached patch in?

The Vicam USB driver in all Linux Kernels 2.6 mainline does not use the 
copy_from_user function when copying data from userspace to kernel space, 
which crosses security boundaries and allows local users to cause a denial
of service.

Already ACKed by Greg. Only complaint was inproper coding style which is done 
with attached patch ;)

ciao, Marc



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diff -urN a/drivers/usb/media/vicam.c b/drivers/usb/media/vicam.c
--- a/drivers/usb/media/vicam.c	2003-11-28 10:26:20.000000000 +0100
+++ b/drivers/usb/media/vicam.c	2004-01-15 12:10:23.000000000 +0100
@@ -653,12 +653,18 @@
 	case VIDIOCSWIN:
 		{
 
-			struct video_window *vw = (struct video_window *) arg;
-			DBG("VIDIOCSWIN %d x %d\n", vw->width, vw->height);
+			struct video_window vw;
 
-			if ( vw->width != 320 || vw->height != 240 )
+			if (copy_from_user(&vw, arg, sizeof(vw))) {
 				retval = -EFAULT;
+				break;
+			}
+
+			DBG("VIDIOCSWIN %d x %d\n", vw->width, vw->height);
 			
+			if ( vw.width != 320 || vw.height != 240 )
+				retval = -EFAULT;
+
 			break;
 		}