linux-kernel - Re: [PATCH v2] staging: lustre: llite: fix potential missing-check bug when copying lumv

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Date:   Fri, 4 May 2018 00:33:46 -0500
From:   Wenwen Wang <wang6495@....edu>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        Aastha Gupta <aastha.gupta4104@...il.com>,
        Roman Storozhenko <romeusmeister@...il.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Jeff Layton <jlayton@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kangjie Lu <kjlu@....edu>, NeilBrown <neilb@...e.com>,
        open list <linux-kernel@...r.kernel.org>,
        Oleg Drokin <oleg.drokin@...el.com>,
        "moderated list:STAGING - LUSTRE PARALLEL FILESYSTEM" 
        <lustre-devel@...ts.lustre.org>, Wenwen Wang <wang6495@....edu>
Subject: Re: [PATCH v2] staging: lustre: llite: fix potential missing-check
 bug when copying lumv

On Fri, May 4, 2018 at 12:27 AM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
> There is no security problem here.  The user is allowed to choose either
> v1 or v3.  Using a double read race condition to choose v1 is not
> going to cause problems.  It's slightly more complicated than just
> choosing it directly but that doesn't make it a security issue.
>
> It's a bit like typing with your feet in that just because using your
> toes instead of your fingergs is more complicated, it doesn't make it a
> security issue.
>
> regards,
> dan carpenter
>

Thanks again for your comment, Dan! I revised the commit message and
removed the security risk:

However, given that the user data resides in the user space, a
malicious user-space process can race to change the data between the
two copies. By doing so, the user can provide a data with an
inconsistent version, e.g., v1 version + v3 data. To improve code
readability and make static analysis tools happy, which will warn
about read-verify-re-read type bugs, this issue should be fixed.

Thanks,

Wenwen