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Mon, 5 Oct 2026 11:22:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791199335; bh=+Ur16o5EMFLYs3ii15Ilcb6PLqZ5R/+UrvQP8v8yGf8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=HuZWN5Us1odcgFzPDx1TIFTAMYvOaGXTqYoEoTbeWe2Om0hHL+qOzldtkgSBWUYZh QCUUJkrhwU+0MTe4I7ItSH1rv/dlyns16z4yuAikMzmF68O3Z9KaxB/LMd5tOBcu4u gL00QF+vSno8AlPdZNroFRYsvR7cqfamI3Yv5UdenzxyytF2m6YmcTY4A6049w3BH3 NRQNtQI4WVy+e7ywsjNosabc+4bm9TynYJW0RG579Sf/+2uH2UmUVqWC0Lz3gre1A4 KOFyx3X6NZxA7USIyXaeyKqNwwFJO6dhpM1FgdABIWZ0w+42yWAAM7DXAKkAr/h03P WlA/xczcpYn6Q== Date: Mon, 5 Oct 2026 04:22:15 -0700 From: Kees Cook To: Andy Shevchenko Cc: Bill Wendling , "Matthew Wilcox (Oracle)" , Andrew Morton , David Gow , Petr Mladek , Shuvam Pandey , Steven Rostedt , Jonathan Corbet , Sergey Senozhatsky , =?iso-8859-1?Q?G=FCnther?= Noack , =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , Masami Hiramatsu , Mathieu Desnoyers , Jiri Kosina , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , "Christophe Leroy (CS GROUP)" , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Shivaprasad G Bhat , Thorsten Blum , Alison Schofield , Dave Jiang , Greg Kroah-Hartman , Guangshuo Li , Ira Weiny , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Vishal Verma , Randy Dunlap , Shuah Khan , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-doc@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v4 05/11] seq_buf: Add seq_buf_strlen() Message-ID: <20261005112209.1e47fa-kees@kernel.org> References: <20261003035906.too.263-kees@kernel.org> <20261003035921.1918874-5-kees@kernel.org> <202610040023.A3865A6@keescook> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sun, Oct 04, 2026 at 11:34:30AM +0300, Andy Shevchenko wrote: > On Sun, Oct 04, 2026 at 12:26:39AM -0700, Kees Cook wrote: > > I'd rather not make all 0-len strings return the .data segment's const > > "" string... > > Good point. Perhaps then to add a short note to the kernel doc, > so we won't see patches based on the suggestion like I gave? Yeah, reasonable. :) For v5 I've added this to seq_buf_str()'s kernel-doc: * A zero-sized seq_buf has nowhere to put a NUL, so the empty string * is returned instead of writing to @s->buffer. Any other seq_buf * returns @s->buffer, even when it holds an empty string, so callers * always get their own buffer back. -Kees -- Kees Cook