From: Alejandro Colomar <alx+linux-hardening@kernel.org>
To: Kees Cook <kees@kernel.org>
Cc: "Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Bill Wendling" <morbo@google.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Gow" <david@davidgow.net>,
"Petr Mladek" <pmladek@suse.com>,
"Shuvam Pandey" <shuvampandey1@gmail.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Sergey Senozhatsky" <senozhatsky@chromium.org>,
"Günther Noack" <gnoack@google.com>,
"Mickaël Salaün" <mic@digikod.net>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Jiri Kosina" <jikos@kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Song Liu" <song@kernel.org>,
"Yonghong Song" <yonghong.song@linux.dev>,
"Jiri Olsa" <jolsa@kernel.org>,
"Emil Tsalapatis" <emil@etsalapatis.com>,
"Ihor Solodrai" <ihor.solodrai@linux.dev>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
"Uwe Kleine-König" <u.kleine-koenig@baylibre.com>,
"Madhavan Srinivasan" <maddy@linux.ibm.com>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Nicholas Piggin" <npiggin@gmail.com>,
"Shivaprasad G Bhat" <sbhat@linux.ibm.com>,
"Thorsten Blum" <blum@kernel.org>,
"Alison Schofield" <alison.schofield@intel.com>,
"Dave Jiang" <dave.jiang@intel.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Guangshuo Li" <lgs201920130244@gmail.com>,
"Ira Weiny" <iweiny@kernel.org>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Vishal Verma" <vishal.l.verma@intel.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Shuah Khan" <skhan@linuxfoundation.org>,
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()
Date: Mon, 5 Oct 2026 13:34:10 +0200 [thread overview]
Message-ID: <asOKvhT01aNb5-Dg@debian> (raw)
In-Reply-To: <20261005112209.1e47fa-kees@kernel.org>
Hi Kees, Andy,
> Date: 2026-10-05 04:22:15-0700
> From: Kees Cook <kees@kernel.org>
>
> 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
>
--
<https://www.alejandro-colomar.es>
next prev parent reply other threads:[~2026-10-05 11:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-03 3:59 [PATCH v4 00/11] " Kees Cook
2026-10-03 3:59 ` [PATCH v4 01/11] seq_buf: Do not print an empty line from an overflowed seq_buf_do_printk() Kees Cook
2026-10-03 4:50 ` bot+bpf-ci
2026-10-05 10:05 ` Kees Cook
2026-10-03 3:59 ` [PATCH v4 02/11] seq_buf: Do not pop from an overflowed seq_buf Kees Cook
2026-10-03 3:59 ` [PATCH v4 03/11] seq_buf: Copy what fits when seq_buf_puts() and seq_buf_putmem() overflow Kees Cook
2026-10-03 4:50 ` bot+bpf-ci
2026-10-05 10:06 ` Kees Cook
2026-10-03 3:59 ` [PATCH v4 04/11] seq_buf: Clear what a writer did not claim when a seq_buf overflows Kees Cook
2026-10-03 4:50 ` bot+bpf-ci
2026-10-03 3:59 ` [PATCH v4 05/11] seq_buf: Add seq_buf_strlen() Kees Cook
2026-10-03 15:36 ` Andy Shevchenko
2026-10-04 7:26 ` Kees Cook
2026-10-04 8:34 ` Andy Shevchenko
2026-10-05 11:22 ` Kees Cook
2026-10-05 11:34 ` Alejandro Colomar [this message]
2026-10-05 15:58 ` Kees Cook
2026-10-05 16:43 ` Alejandro Colomar
2026-10-03 3:59 ` [PATCH v4 06/11] seq_buf: Add seq_buf_terminate() Kees Cook
2026-10-03 3:59 ` [PATCH v4 07/11] bpf: Remove dead newline stripping from format_disasm_line() Kees Cook
2026-10-03 3:59 ` [PATCH v4 08/11] seq_buf: Add seq_buf_init_append() Kees Cook
2026-10-03 4:33 ` bot+bpf-ci
2026-10-03 10:31 ` Kees Cook
2026-10-03 3:59 ` [PATCH v4 09/11] powerpc/papr_scm: Return the string length from the sysfs show functions Kees Cook
2026-10-03 3:59 ` [PATCH v4 10/11] nvdimm: ndtest: Return the string length from flags_show() Kees Cook
2026-10-03 3:59 ` [PATCH v4 11/11] docs: core-api: Document the seq_buf API Kees Cook
2026-10-03 6:32 ` [PATCH v4 00/11] seq_buf: Add seq_buf_strlen() Alexei Starovoitov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=asOKvhT01aNb5-Dg@debian \
--to=alx+linux-hardening@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=alison.schofield@intel.com \
--cc=andrii@kernel.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=ast@kernel.org \
--cc=blum@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=chleroy@kernel.org \
--cc=corbet@lwn.net \
--cc=daniel@iogearbox.net \
--cc=dave.jiang@intel.com \
--cc=david@davidgow.net \
--cc=eddyz87@gmail.com \
--cc=emil@etsalapatis.com \
--cc=gnoack@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=ihor.solodrai@linux.dev \
--cc=iweiny@kernel.org \
--cc=jikos@kernel.org \
--cc=jolsa@kernel.org \
--cc=kees@kernel.org \
--cc=lgs201920130244@gmail.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=maddy@linux.ibm.com \
--cc=martin.lau@linux.dev \
--cc=mathieu.desnoyers@efficios.com \
--cc=memxor@gmail.com \
--cc=mhiramat@kernel.org \
--cc=mic@digikod.net \
--cc=morbo@google.com \
--cc=mpe@ellerman.id.au \
--cc=npiggin@gmail.com \
--cc=nvdimm@lists.linux.dev \
--cc=pmladek@suse.com \
--cc=rdunlap@infradead.org \
--cc=rostedt@goodmis.org \
--cc=sbhat@linux.ibm.com \
--cc=senozhatsky@chromium.org \
--cc=shuvampandey1@gmail.com \
--cc=skhan@linuxfoundation.org \
--cc=song@kernel.org \
--cc=u.kleine-koenig@baylibre.com \
--cc=u.kleine-koenig@pengutronix.de \
--cc=vishal.l.verma@intel.com \
--cc=willy@infradead.org \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®