Re: mpol_to_str revisited.

From: KOSAKI Motohiro
Date: Mon Oct 15 2012 - 22:35:11 EST


On Mon, Oct 8, 2012 at 11:09 AM, Dave Jones <davej@xxxxxxxxxx> wrote:
> Last month I sent in 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a to remove
> a user triggerable BUG in mempolicy.
>
> Ben Hutchings pointed out to me that my change introduced a potential leak
> of stack contents to userspace, because none of the callers check the return value.
>
> This patch adds the missing return checking, and also clears the buffer beforehand.

I don't think 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a is right fix. we should
close a race (or kill remain ref count leak) if we still have.
Because of, this patch makes unstable /proc output and might lead to
userland confusing.
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