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Date:   Wed, 18 Aug 2021 11:28:27 +0200
From:   David Sterba <dsterba@suse.cz>
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org, Chris Mason <clm@fb.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>, linux-btrfs@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev,
        linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2 49/63] btrfs: Use memset_startat() to clear end of
 struct
Message-ID: <20210818092827.GO5047@twin.jikos.cz>
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        Josef Bacik <josef@toxicpanda.com>, David Sterba <dsterba@suse.com>,
        linux-btrfs@vger.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev,
        linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        linux-hardening@vger.kernel.org
References: <20210818060533.3569517-1-keescook@chromium.org>
 <20210818060533.3569517-50-keescook@chromium.org>
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On Tue, Aug 17, 2021 at 11:05:19PM -0700, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
> 
> Use memset_startat() so memset() doesn't get confused about writing
> beyond the destination member that is intended to be the starting point
> of zeroing through the end of the struct.
> 
> Cc: Chris Mason <clm@fb.com>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: David Sterba <dsterba@suse.com>
> Cc: linux-btrfs@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Acked-by: David Sterba <dsterba@suse.com>