linux-kernel - Re: [PATCH v2 01/20] NFS: Avoid cross-structure casting

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Message-ID: <CAGXu5jL3w=y_EXA9cdx-6VUhKDaGpSFSxJsY+iP_ocf54A4MdQ@mail.gmail.com>
Date:   Sun, 28 May 2017 09:55:37 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        Laura Abbott <labbott@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 01/20] NFS: Avoid cross-structure casting

On Sun, May 28, 2017 at 12:53 AM, Christoph Hellwig <hch@...radead.org> wrote:
> On Fri, May 26, 2017 at 01:17:05PM -0700, Kees Cook wrote:
>> When the call to nfs_devname() fails, the error path attempts to retain
>> the error via the mnt variable, but this requires a cast across very
>> different types (char * to struct vfsmount *), which the upcoming
>> structure layout randomization plugin flags as being potentially
>> dangerous in the face of randomization. This is a false positive, but
>> what this code actually wants to do is retain the error value, so this
>> patch explicitly sets it, instead of using what seems to be an
>> unexpected cast.
>>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> Acked-by: Trond Myklebust <trond.myklebust@...marydata.com>
>
> Looks good:
>
> Reviewed-by: Christoph Hellwig <hch@....de>
>
> And I think we should get this (and the other cast patches) in ASAP,
> independent of the fat of the randstruct plugin.

Should I send a pull request to Linus for these for v4.12?

-Kees

-- 
Kees Cook
Pixel Security