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From: David Laight <David.Laight@ACULAB.COM>
To: 'Borislav Petkov' <bp@alien8.de>, Len Baker <len.baker@gmx.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Tony Luck <tony.luck@intel.com>,
	James Morse <james.morse@arm.com>,
	Robert Richter <rric@kernel.org>, Joe Perches <joe@perches.com>,
	Kees Cook <keescook@chromium.org>,
	"linux-hardening@vger.kernel.org"
	<linux-hardening@vger.kernel.org>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v4] EDAC/mc: Prefer strscpy over strcpy
Date: Wed, 25 Aug 2021 08:48:03 +0000	[thread overview]
Message-ID: <a45274ec2e454323a37cde36bb365e97@AcuMS.aculab.com> (raw)
In-Reply-To: <YSU5wp/ZpsXuDgmu@zn.tnic>

From: Borislav Petkov
> Sent: 24 August 2021 19:26
..
> so looking at the code, we're merrily decrementing len but nothing's
> checking whether len can become 0. Because if it does, strscpy() will
> do:
> 
> 	if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
> 		return -E2BIG;

That -E2BIG is going to break something.
It means that you always have to do an error check whenever
you use the return value of strscpy().

Anything that does:
	offset += strscpy(...)
is broken.

It really wasn't a good idea for reporting 'truncated'.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  parent reply	other threads:[~2021-08-25  8:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-14  7:55 Len Baker
2021-08-23 17:30 ` Borislav Petkov
2021-08-24 10:28   ` Len Baker
2021-08-24 18:26     ` Borislav Petkov
2021-08-24 19:05       ` Joe Perches
2021-08-25  8:48       ` David Laight [this message]
2021-08-27 17:36       ` Len Baker
2021-08-27 17:54         ` Borislav Petkov
2021-08-27 19:08           ` Joe Perches
2021-08-29 16:14           ` Len Baker

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