linux-hardening - Re: the nul-terminated string helper desk chair rearrangement

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231020044645.GC11984@lst.de>
Date: Fri, 20 Oct 2023 06:46:45 +0200
From: Christoph Hellwig <hch@....de>
To: Kees Cook <keescook@...omium.org>
Cc: Christoph Hellwig <hch@....de>, Justin Stitt <justinstitt@...gle.com>,
	Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>,
	Sagi Grimberg <sagi@...mberg.me>, linux-nvme@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
	ksummit@...ts.linux.dev
Subject: Re: the nul-terminated string helper desk chair rearrangement

On Wed, Oct 18, 2023 at 11:01:54PM -0700, Kees Cook wrote:
> Almost all of the remaining strncpy() usage is just string to string
> copying, but the corner cases that are being spun out that aren't
> strscpy() or strscpy_pad() are covered by strtomem(), kmemdup_nul(),
> and memcpy(). Each of these are a clear improvement since they remove
> the ambiguity of the intended behavior. Using seq_buf ends up being way
> more overhead than is needed.

I'm really not sure strscpy is much of an improvement.  In this particular
case in most other places we simply use a snprintf for nqns, which seems
useful here to if we don't want the full buf.

But switching to a completely undocumented helper like strscpy seems not
useful at all.