linux-kernel - Re: [PATCH v2] hex2bin: fix access beyond string end

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Message-ID: <YmfxCxbneEcs44Ch@smile.fi.intel.com>
Date:   Tue, 26 Apr 2022 16:18:03 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Mikulas Patocka <mpatocka@...hat.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Shevchenko <andy@...nel.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        device-mapper development <dm-devel@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mike Snitzer <msnitzer@...hat.com>,
        Milan Broz <gmazyland@...il.com>
Subject: Re: [PATCH v2] hex2bin: fix access beyond string end

On Tue, Apr 26, 2022 at 08:07:44AM -0400, Mikulas Patocka wrote:
> On Tue, 26 Apr 2022, Andy Shevchenko wrote:
> > On Sun, Apr 24, 2022 at 10:48 PM Mikulas Patocka <mpatocka@...hat.com> wrote:
> > >
> > > If we pass too short string to "hex2bin" (and the string size without the
> > > terminating NUL character is even), "hex2bin" reads one byte after the
> > > terminating NUL character. This patch fixes it.
> > >
> > > Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
> > > Cc: stable@...r.kernel.org
> > 
> > You need to provide a Fixes tag.
> 
> OK. Here I resend it with the "Fixes" tag.
> 
> > And on top of that it would be nice to understand if we need to
> > support half-bytes, but in any case it's not a scope of the patch
> > right now.
> 
> Do you think that there are any users who need this?

If my memory doesn't do any tricks with me, I have seen the patterns like
hex2bin() + hex_to_bin() in some places in the kernel.

-- 
With Best Regards,
Andy Shevchenko