linux-kernel - Re: [PATCH v2] fs: binfmt_elf: Add ELF header consistency checks

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Message-ID: <20131121013918.GI10323@ZenIV.linux.org.uk>
Date:	Thu, 21 Nov 2013 01:39:19 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	"Geyslan G. Bem" <geyslan@...il.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-br@...glegroups.com
Subject: Re: [PATCH v2] fs: binfmt_elf: Add ELF header consistency checks

On Wed, Nov 20, 2013 at 09:34:31PM -0300, Geyslan G. Bem wrote:
> The member 'e_ehsize' that holds the ELF header size is compared
> with the elfhdr struct size. If not equal, goes out.
> If 'e_phoff' holds 0 the object has no program header table, so
> goes out.
> Ensures the file being loaded has the correct data encoding, checking
> 'e_ident[EI_DATA]' against 'ELF_DATA'.
> 
> Besides the checks being in accordance with the ELF Specifications,
> they increase the binary consistency reducing the use of malformed ones.

This is completely misguided.  We are allowed to reject such binaries,
but what's the point of doing that?
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