linux-kernel - Re: [PATCH v3 2/4] mm/page_owner: Use scnprintf() to avoid excessive buffer overrun check

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Message-ID: <YfhI1QHRL34QMOCu@carbon.dhcp.thefacebook.com>
Date:   Mon, 31 Jan 2022 12:38:45 -0800
From:   Roman Gushchin <guro@...com>
To:     Waiman Long <longman@...hat.com>
CC:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        <linux-kernel@...r.kernel.org>, <cgroups@...r.kernel.org>,
        <linux-mm@...ck.org>, Ira Weiny <ira.weiny@...el.com>,
        Mike Rapoport <rppt@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Rafael Aquini <aquini@...hat.com>
Subject: Re: [PATCH v3 2/4] mm/page_owner: Use scnprintf() to avoid excessive
 buffer overrun check

On Mon, Jan 31, 2022 at 02:23:06PM -0500, Waiman Long wrote:
> The snprintf() function can return a length greater than the given
> input size. That will require a check for buffer overrun after each
> invocation of snprintf(). scnprintf(), on the other hand, will never
> return a greater length. By using scnprintf() in selected places, we
> can avoid some buffer overrun checks except after stack_depot_snprint()
> and after the last snprintf().
> 
> Signed-off-by: Waiman Long <longman@...hat.com>
> Acked-by: David Rientjes <rientjes@...gle.com>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>

Acked-by: Roman Gushchin <guro@...com>