linux-kernel - Re: [RFC 0/7] eliminate snprintf with overlapping src and dst

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Message-Id: <20160309124940.7d870c59a7a7117c6c6d7937@linux-foundation.org>
Date:	Wed, 9 Mar 2016 12:49:40 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC 0/7] eliminate snprintf with overlapping src and dst

On Tue,  8 Mar 2016 21:40:47 +0100 Rasmus Villemoes <linux@...musvillemoes.dk> wrote:

> Doing snprintf(buf, len, "%s...", buf, ...) for appending to a buffer
> currently works, but it is somewhat fragile, and any other overlap
> between source and destination buffers would be a definite bug. This
> is an attempt at eliminating the relatively few occurences of this
> pattern in the kernel.

I dunno,

	snprintf(analog->name, sizeof(analog->name), "Analog %d-axis %d-button",

is pretty damn convenient.  Can we instead state that "sprintf shall
support this"?  Maybe add a little __init testcase to vsprintf.c to
check that it continues to work OK.