linux-kernel - Re: [PATCH 16/23] pefile: Parse a PE binary to find a key and a signature contained therein

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Message-ID: <23121.1351645166@warthog.procyon.org.uk>
Date:	Wed, 31 Oct 2012 00:59:26 +0000
From:	David Howells <dhowells@...hat.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	dhowells@...hat.com, rusty@...tcorp.com.au, pjones@...hat.com,
	jwboyer@...hat.com, mjg@...hat.com, dmitry.kasatkin@...el.com,
	zohar@...ux.vnet.ibm.com, keyrings@...ux-nfs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 16/23] pefile: Parse a PE binary to find a key and a signature contained therein

Kees Cook <keescook@...omium.org> wrote:

> This multiplication can push the cursor out of bounds. (n_data_dirents
> is unverified).
> ...
> Both of these cases of n_sections multiplications can wrap.
> Ultimately, you can end up with cursor close to zero, but n_sections
> being giant.

Good points.  I wonder if I should limit these to some low number, or just
check that they don't exceed header_size, which also needs checking as you
said.

> ... (Also, do you want a "break" in there after the first .keylist is found,
> or is this intentionally "use last key list"?)

I hadn't considered that.  Inserting a break is probably best, if only to
curtail the processing time slightly.

David
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