linux-kernel - Re: [PATCH v2] fs: make d_path-like functions all have unsigned size

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: <YP/+g/L6+tLWjx/l@smile.fi.intel.com>
Date:   Tue, 27 Jul 2021 15:39:31 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jordy Zomer <jordy@...ing.systems>,
        "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Eric Biggers <ebiggers@...gle.com>
Subject: Re: [PATCH v2] fs: make d_path-like functions all have unsigned size

On Tue, Jul 27, 2021 at 02:07:54PM +0200, Greg Kroah-Hartman wrote:
> When running static analysis tools to find where signed values could
> potentially wrap the family of d_path() functions turn out to trigger a
> lot of mess.  In evaluating the code, all of these usages seem safe, but
> pointer math is involved so if a negative number is ever somehow passed
> into these functions, memory can be traversed backwards in ways not
> intended.
> 
> Resolve all of the abuguity by just making "size" an unsigned value,
> which takes the guesswork out of everything involved.

Are you sure it's correct change?

Look into extract_string() implementation.

	if (likely(p->len >= 0))
		return p->buf;
	return ERR_PTR(-ENAMETOOLONG);

Your change makes it equal to

	return p->buf;

if I'm not mistaken.

-- 
With Best Regards,
Andy Shevchenko