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Tue, 19 Sep 2023 06:55:47 -0700 (PDT) MIME-Version: 1.0 References: <20230919080707.1077426-1-max.kellermann@ionos.com> <20230919-fachkenntnis-seenotrettung-3f873c1ec8da@brauner> In-Reply-To: <20230919-fachkenntnis-seenotrettung-3f873c1ec8da@brauner> From: Max Kellermann Date: Tue, 19 Sep 2023 15:55:36 +0200 Message-ID: Subject: Re: [PATCH] pipe_fs_i.h: add pipe_buf_init() To: Christian Brauner Cc: Alexander Viro , "Matthew Wilcox (Oracle)" , Andrew Morton , Hugh Dickins , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 0942D8002A X-Rspam-User: X-Stat-Signature: qpscrw5bu3j53zj66m46hfdgtqx1cbsz X-Rspamd-Server: rspam03 X-HE-Tag: 1695131748-413838 X-HE-Meta: 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 U6Rx+gNz Hsstg68MPiwKjVz54gfGQqX3E053nUN1bkcVj3zVWJaq3RtcRSFK1nNkyDwQNWhGbJl44i/pOZ8P09lzM8rB8JMaLj9iDpObkoRFTADuVdC7RoOIjEW4gFFcJfGZljU3fgBQQjOi7paRyRA0SJHvlwq2/0OLMeFPQR7/uckDDUiklYL+X//JapesalZzovCmynzDD/rUIYPxPsv0g27038+hBhts/XKym+zK0EwyJV2W6XzJHp7xemnWe1pbUe6yhLDJIfc3sbs0XscfVKJBRssELa0idx/U9K7cFd4kwmMoxRTVIxV3pqxqAaRlh3qShfKoZ6WTRVmbSWHM/RVlbPNVITO99oYkrlubX X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 19, 2023 at 3:45=E2=80=AFPM Christian Brauner wrote: > So pipe_buf->private may now contain garbage. NULL is just as garbage as the other 2^64-1 possible pointer values. NULL isn't special here, nobody checks the field for NULL. This field is specially crafted for exactly one user, and initializing it with NULL for all others will at best only add unnecessary overhead, and at worst will hide initialization bugs from sanitiziers who now think it's indeed properly initialized. > Does the helper buy us that much overall? This is about introducing a safer coding style. The lack of a central initializer function is what caused CVE-2022-0847, which was the worst security vulnerability in a decade or two.