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Mon, 5 Oct 2026 11:34:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 592031F000FF; Mon, 5 Oct 2026 11:34:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791200072; bh=GfHzSlHJ8UI5Oxtdm8BU7e9P310nmqwzsr8Vwb26i2M=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=LGu7cFHiLoleVxKaNXEWg3+hk4n4alCXvLuprPWQEhjOKkys62HeJhx/UbENV031V vIn/6TtJtxJ4vVZb9rnXmiywGirW0RgkjvnuB58tASjcVtU6wkVSS2shU+C/HAHFbp KlgEOWVTWGCe7lgJrWwgepyszO2dtI/ANUif+WUxrjQTe62Dep2+QJVwl3tBvdSTPQ 8tdIKlDYRdYPxPlJ1II3h6zxg0tiajgIXcEHp0czbPWMG/jqrvSNQIebFQEBDguOoU zgLw8YhUIYuFxKCCDsOuzd1eZh0m0cOUc1RtREjfI7QsJ5nwq45p57p9GTKfZsiN69 fwUMLC3DnyLNg== Date: Mon, 5 Oct 2026 13:34:10 +0200 From: Alejandro Colomar To: Kees Cook Cc: Andy Shevchenko , Bill Wendling , "Matthew Wilcox (Oracle)" , Andrew Morton , David Gow , Petr Mladek , Shuvam Pandey , Steven Rostedt , Jonathan Corbet , Sergey Senozhatsky , =?utf-8?Q?G=C3=BCnther?= Noack , =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= , 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 =?utf-8?Q?Kleine-K=C3=B6nig?= , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Shivaprasad G Bhat , Thorsten Blum , Alison Schofield , Dave Jiang , Greg Kroah-Hartman , Guangshuo Li , Ira Weiny , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , 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: References: <20261003035906.too.263-kees@kernel.org> <20261003035921.1918874-5-kees@kernel.org> <202610040023.A3865A6@keescook> <20261005112209.1e47fa-kees@kernel.org> 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=utf-8 Content-Disposition: inline In-Reply-To: <20261005112209.1e47fa-kees@kernel.org> Hi Kees, Andy, > Date: 2026-10-05 04:22:15-0700 > From: Kees Cook > > 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. Are such buffers actually used on purpose anywhere? Why not keep the WARN_ON? Have a lovely day! Alex > > -Kees > > -- > Kees Cook > --