linux-kernel - Re: [PATCH][next] ima: ima_modsig: Fix use-after-free bug in ima_read

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Date:   Wed, 28 Aug 2019 09:50:15 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] ima: ima_modsig: Fix use-after-free bug in
 ima_read_modsig

Hi Gustavo,

On Sun, 2019-08-11 at 18:55 -0500, Gustavo A. R. Silva wrote:
> hdr is being freed and then dereferenced by accessing hdr->pkcs7_msg
> 
> Fix this by copying the value returned by PTR_ERR(hdr->pkcs7_msg) into
> automatic variable err for its safe use after freeing hdr.
> 
> Addresses-Coverity-ID: 1485813 ("Read from pointer after free")
> Fixes: 39b07096364a ("ima: Implement support for module-style appended signatures")
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

This bug was reported Julia and addressed by Thiago on 8/7. If you
would like to add your Review/Tested-by, the patch can be found in the
linux-integrity next-queued-testing branch.

thanks,

Mimi