Re: [PATCH] wireless: fix 64K kernel heap content leak via ioctl

Jean Tourrilhes
2010-08-30T17:40:54Z

On Mon, Aug 30, 2010 at 11:59:01AM +0200, Johannes Berg wrote:
>
> Ok I finally fully understood the issue.
>
> This will fix the problem, but the comment is completely bogus, which I
> guess means you didn't actually understand the problem.

Correct, Kees pointed out that my comment was bogus and the
e-mail I sent after the patch corrected myself on that point :

------------------------------------
> The comment should probably be clarified -- it's the caller's iwp->length
> that may be causing problems

Ha ! I see. It would be for regular iwpoint queries, not for
extended NOMAX queries (scan is a extended NOMAX query).
------------------------------------

> My patch also didn't fix the problem, I didn't understand the problem
> correctly and was continuously wondering how drivers would ever fill the
> buffer with more than max_tokens (which would be a more serious bug,
> since they'd overwrite a slab object after "extra").

Yes, I had arrived at the same conclusion (not that my patch
did fix the issue).

> What really fixes the problem is the patch below though. Had to realise
> that the path where the driver didn't do ANYTHING AT ALL was the
> problem....

I actually like your patch better than mine, it's closer to
the original intent of the API. Go for it ;-)

> johannes

Thanks a lot for the second pair of eyes.

Jean