linux-hardening - RE: [RFC] string: Allow 2-argument strscpy()

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Message-ID: <9dae4c62fc164abeaa7915f9e53fdb28@AcuMS.aculab.com>
Date: Thu, 1 Feb 2024 22:29:37 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Kees Cook' <keescook@...omium.org>, Andy Shevchenko <andy@...nel.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
CC: "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFC] string: Allow 2-argument strscpy()

From: Kees Cook
> Sent: 29 January 2024 20:29
> 
> Using sizeof(dst) is the overwhelmingly common case for strscpy().
> Instead of requiring this everywhere, allow a 2-argument version to be
> used that will use the sizeof() internally.

You may want to (try to) add a check that the first argument is
actually an array rather than just a pointer.

But the cpp output bloat can get silly and slow the build down.
I guess no one would do:
	x = min(strscpy(a, b), strscpy(c, d));
but you can never tell :-)

	David

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