netdev - Re: [PATCH v8 1/8] Get rid of __get_task

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: <ynrircglkinhherehtjz7woq55te55y4ol4rtxhfh75pvle3d5@uxp5esxt4slq>
Date: Wed, 28 Aug 2024 17:09:08 +0200
From: Alejandro Colomar <alx@...nel.org>
To: Kees Cook <kees@...nel.org>
Cc: Yafang Shao <laoar.shao@...il.com>, akpm@...ux-foundation.org, 
	torvalds@...ux-foundation.org, justinstitt@...gle.com, ebiederm@...ssion.com, 
	alexei.starovoitov@...il.com, rostedt@...dmis.org, catalin.marinas@....com, 
	penguin-kernel@...ove.sakura.ne.jp, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org, audit@...r.kernel.org, linux-security-module@...r.kernel.org, 
	selinux@...r.kernel.org, bpf@...r.kernel.org, netdev@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, Kees Cook <keescook@...omium.org>, 
	Matus Jokay <matus.jokay@...ba.sk>, "Serge E. Hallyn" <serge@...lyn.com>
Subject: Re: [PATCH v8 1/8] Get rid of __get_task_comm()

Hi Kees,

On Wed, Aug 28, 2024 at 06:48:39AM GMT, Kees Cook wrote:

[...]

> >Thank you for your suggestion. How does the following commit log look
> >to you? Does it meet your expectations?
> >
> >    string: Use ARRAY_SIZE() in strscpy()
> >
> >    We can use ARRAY_SIZE() instead to clarify that they are regular characters.
> >
> >    Co-developed-by: Alejandro Colomar <alx@...nel.org>
> >    Signed-off-by: Alejandro Colomar <alx@...nel.org>
> >    Signed-off-by: Yafang Shao <laoar.shao@...il.com>
> >
> >diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
> >index bbab79c0c074..07216996e3a9 100644
> >--- a/arch/um/include/shared/user.h
> >+++ b/arch/um/include/shared/user.h
> >@@ -14,7 +14,7 @@
> >  * copying too much infrastructure for my taste, so userspace files
> >  * get less checking than kernel files.
> >  */
> >-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> >+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]) + __must_be_array(x))
> >
> > /* This is to get size_t and NULL */
> > #ifndef __UM_HOST__
> >@@ -60,7 +60,7 @@ static inline void print_hex_dump(const char *level,
> >const char *prefix_str,
> > extern int in_aton(char *str);
> > extern size_t strlcat(char *, const char *, size_t);
> > extern size_t sized_strscpy(char *, const char *, size_t);
> >-#define strscpy(dst, src)      sized_strscpy(dst, src, sizeof(dst))
> >+#define strscpy(dst, src)      sized_strscpy(dst, src, ARRAY_SIZE(dst))
> 
> Uh, but why? strscpy() copies bytes, not array elements. Using sizeof() is already correct and using ARRAY_SIZE() could lead to unexpectedly small counts (in admittedly odd situations).
> 
> What is the problem you're trying to solve here?

I suggested that here:
<https://lore.kernel.org/all/2jxak5v6dfxlpbxhpm3ey7oup4g2lnr3ueurfbosf5wdo65dk4@srb3hsk72zwq/>

There, you'll find the rationale (and also for avoiding the _pad calls
where not necessary --I ignore if it's necessary here--).

Have a lovely day!
Alex

> 
> -Kees
> 
> -- 
> Kees Cook

-- 
<https://www.alejandro-colomar.es/>

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)