linux-kernel - Re: [Linux-ima-devel] [PATCH 0/7] IMA: new parser for ima_restore_measurement

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Message-Id: <96385c1f-26f9-989b-3b68-0ad261e927b5@linux.vnet.ibm.com>
Date:   Tue, 23 May 2017 17:00:27 -0400
From:   Ken Goldman <kgold@...ux.vnet.ibm.com>
To:     linux-ima-devel@...ts.sourceforge.net
Cc:     linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Linux-ima-devel] [PATCH 0/7] IMA: new parser for
 ima_restore_measurement_list()

On 5/18/2017 5:38 AM, Roberto Sassu wrote:
> 
> There cannot be buffer overflow, because the length of each digest
> field is known.

Crypto Agile: pcr[4] total_digest_len[4]
                digest1_len[4] digest1[digest1_len] ...

The way I read this, the digest length is supplied by the caller, which 
is slightly different from "known".  For example, if I supply a digest 
length of 0xffffffff, a too trusting (buggy) parser could overflow the 
buffer.

total_digest_len is similarly untrusted.  The attacker can send invalid 
values.