linux-kernel - Re: [oss-security] Re: [PATCH v2 4/4] ozwpan: unchecked signed subtraction leads to DoS

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Message-ID: <CAHmME9oPvTzmi17Ec1R0Gm=-2ZTjkVL_LE0rTGy9sKJXOXDFEw@mail.gmail.com>
Date:	Tue, 26 May 2015 16:34:55 +0200
From:	"Jason A. Donenfeld" <Jason@...c4.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	linux-kernel@...r.kernel.org,
	Shigekatsu Tateno <shigekatsu.tateno@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org
Subject: Re: [oss-security] Re: [PATCH v2 4/4] ozwpan: unchecked signed
 subtraction leads to DoS

On Tue, May 26, 2015 at 4:06 PM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
> You sure do like wrapping to a high value and testing the result for
> wrapping instead of validating before doing the subtraction...

I do indeed. It seems like asking "did it overflow?" is more
straight-forward and easier to read than trying to come up with the
necessary conditions to check for "will it overflow?". Personal
preference, I guess.
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