lkml.org 
[lkml]   [2006]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 49/61] ISDN: fix drivers, by handling errors thrown by ->readstat()
On Wed, Nov 01, 2006 at 08:49:22AM +0100, Willy Tarreau wrote:
> On Tue, Oct 31, 2006 at 09:34:29PM -0800, Chris Wright wrote:
> > -stable review patch. If anyone has any objections, please let us know.
> > ------------------
> >
> > From: Jeff Garzik <jeff@garzik.org>
> >
> > This is a particularly ugly on-failure bug, possibly security, since the
> > lack of error handling here is covering up another class of bug: failure to
> > handle copy_to_user() return values.
> >
> > The I4L API function ->readstat() returns an integer, and by looking at
> > several existing driver implementations, it is clear that a negative return
> > value was meant to indicate an error.
> >
> > Given that several drivers already return a negative value indicating an
> > errno-style error, the current code would blindly accept that [negative]
> > value as a valid amount of bytes read. Obvious damage ensues.
> >
> > Correcting ->readstat() handling to properly notice errors fixes the
> > existing code to work correctly on error, and enables future patches to
> > more easily indicate errors during operation.
> >
> > Signed-off-by: Jeff Garzik <jeff@garzik.org>
> > Cc: Karsten Keil <kkeil@suse.de>
> > Cc: <stable@kernel.org>
> > Signed-off-by: Andrew Morton <akpm@osdl.org>
> > Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> > Signed-off-by: Chris Wright <chrisw@sous-sol.org>
> > ---
> > drivers/isdn/i4l/isdn_common.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > --- linux-2.6.18.1.orig/drivers/isdn/i4l/isdn_common.c
> > +++ linux-2.6.18.1/drivers/isdn/i4l/isdn_common.c
> > @@ -1134,9 +1134,12 @@ isdn_read(struct file *file, char __user
> > if (dev->drv[drvidx]->interface->readstat) {
> > if (count > dev->drv[drvidx]->stavail)
> > count = dev->drv[drvidx]->stavail;
> > - len = dev->drv[drvidx]->interface->
> > - readstat(buf, count, drvidx,
> > - isdn_minor2chan(minor));
> > + len = dev->drv[drvidx]->interface->readstat(buf, count,
> > + drvidx, isdn_minor2chan(minor));
> > + if (len < 0) {
> > + retval = len;
> > + goto out;
> > + }
> > } else {
> > len = 0;
> > }
>
> Seems appropriate for 2.4 too. Jeff, Karsten, no objection ?
>

Yes, OK for me.

--
Karsten Keil
SuSE Labs
ISDN development
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-01 10:21    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site