From: Peter Jones <pjones@redhat.com>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: linux-efi@vger.kernel.org, Jason Andryuk <jandryuk@gmail.com>,
intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
Matthew Garrett <mjg59@coreos.com>,
Laszlo Ersek <lersek@redhat.com>
Subject: Re: [PATCH] lib: Always NUL terminate ucs2_as_utf8
Date: Thu, 21 Apr 2016 11:13:44 -0400 [thread overview]
Message-ID: <20160421151343.GA3763@redhat.com> (raw)
In-Reply-To: <20160421121827.GE2829@codeblueprint.co.uk>
On Thu, Apr 21, 2016 at 01:18:27PM +0100, Matt Fleming wrote:
> ( Good Lord, I hate doing string manipulation in C )
(yep)
>
> On Wed, 20 Apr, at 03:25:32PM, Laszlo Ersek wrote:
> >
> > So, "len" does not include the room for the terminating NUL-byte here.
> > When "len" is passed to ucs2_as_utf8(), with the proposed patch applied,
> > a NUL byte will be produced in "name", but it will be at the price of a
> > genuine character from the input variable name.
>
> Right, and this is a problem because we're trying to keep the names
> consistent between efivarfs and the EFI variable data. Force
> NUL-terminating the string is wrong, because if you have no room for
> the NUL the caller should check for that. Sadly none do.
>
> On the flip-side, passing around non-NUL terminated strings is just
> begging for these kinds of issues to come up.
>
> The fact is that the callers of ucs2_as_utf8() are passing it the
> wrong 'len' argument. We want a NUL-terminated utf8 string and we're
> passing a NUL-terminated ucs2 string. We should tell ucs2_as_utf8() it
> has enough room to copy the NUL.
>
> Wouldn't this work (minus the return value checking)?
I agree with your analysis, and your patch looks plausible.
--
Peter
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next prev parent reply other threads:[~2016-04-21 15:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-20 8:37 [PATCH] lib: Always NUL terminate ucs2_as_utf8 Chris Wilson
[not found] ` <1461141427-16361-1-git-send-email-chris-Y6uKTt2uX1cEflXRtASbqLVCufUGDwFn@public.gmane.org>
2016-04-20 9:36 ` Laszlo Ersek
2016-04-20 9:41 ` Chris Wilson
2016-04-20 12:45 ` Laszlo Ersek
2016-04-20 13:25 ` Laszlo Ersek
[not found] ` <5717834C.6070802-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-04-21 12:18 ` Matt Fleming
2016-04-21 15:13 ` Peter Jones [this message]
2016-04-21 16:21 ` Laszlo Ersek
2016-04-22 18:52 ` Matt Fleming
[not found] ` <20160422185210.GG2829-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2016-04-25 10:17 ` Laszlo Ersek
2016-04-20 14:03 ` [Intel-gfx] " Jani Nikula
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