linux-kernel - Re: [PATCH v2 1/9] sysctl: fix lax sysctl_check

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Message-ID: <CAGXu5j+YW0K+7X8dwpx2EQr9GwscXzv2=PS7ppxdnweJFo_C2A@mail.gmail.com>
Date:   Mon, 13 Feb 2017 12:13:45 -0800
From:   Kees Cook <keescook@...omium.org>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, Mel Gorman <mgorman@...e.de>,
        Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>,
        Jessica Yu <jeyu@...hat.com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        Steven Whitehouse <swhiteho@...hat.com>,
        deepa.kernel@...il.com, Matt Fleming <matt@...eblueprint.co.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Borislav Petkov <bp@...e.de>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>, shuah@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kselftest@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/9] sysctl: fix lax sysctl_check_table() sanity check

On Fri, Feb 10, 2017 at 4:36 PM, Luis R. Rodriguez <mcgrof@...nel.org> wrote:
> Commit 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks")
> improved sanity checks considerbly, however the enhancements on
> sysctl_check_table() meant adding a functional change so that
> only the last table entry's sanity error is propagated. It also
> changed the way errors were propagated so that each new check
> reset the err value, this means only last sanity check computed
> is used for an error. This has been in the kernel since v3.4 days.
>
> Fix this by carrying on errors from previous checks and iterations
> as we traverse the table and ensuring we keep any error from previous
> checks. We keep iterating on the table even if an error is found so
> we can complain for all errors found in one shot. This works as
> -EINVAL is always returned on error anyway, and the check for error
> is any non-zero value.

I assume this didn't catch anything that was broken-but-hidden in the kernel?

>
> Fixes: 7c60c48f58a7 ("sysctl: Improve the sysctl sanity checks")
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

-- 
Kees Cook
Pixel Security