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 <[email protected]>
>
> 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 <[email protected]>
> Cc: Karsten Keil <[email protected]>
> Cc: <[email protected]>
> Signed-off-by: Andrew Morton <[email protected]>
> Signed-off-by: Linus Torvalds <[email protected]>
> Signed-off-by: Chris Wright <[email protected]>
> ---
> 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 ?
Willy
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