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SubjectRe: [PATCH 49/61] ISDN: fix drivers, by handling errors thrown by ->readstat()
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>

No objection, but I would think that you would also want the companion
patch:

commit 7786ce192fc4917fb9b789dd823476ff8fd6cf66
Author: Jeff Garzik <jeff@garzik.org>
Date: Tue Oct 17 00:10:40 2006 -0700

[PATCH] ISDN: check for userspace copy faults

Most of the ISDN ->readstat() implementations needed to check
copy_to_user() and put_user() return values.


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