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Subject: Re: [PATCH] ima: dynamically allocate shash_desc
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Arnd Bergmann <arnd@arndb.de>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Stefan Berger <stefanb@linux.vnet.ibm.com>,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 17 Jun 2019 14:07:06 -0400
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         <1560786951.4072.103.camel@linux.ibm.com>
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On Mon, 2019-06-17 at 11:55 -0400, Mimi Zohar wrote:
> On Mon, 2019-06-17 at 13:20 +0200, Arnd Bergmann wrote:
> > On 32-bit ARM, we get a warning about excessive stack usage when
> > building with clang.
> > 
> > security/integrity/ima/ima_crypto.c:504:5: error: stack frame size
> > of 1152 bytes in function 'ima_calc_field_array_hash' [-Werror,-
> > Wframe-larger-than=]
> 
> I'm definitely not seeing this.  Is this problem a result of non
> upstreamed patches?  For sha1, currently the only possible hash
> algorithm, I'm seeing 664.

Every time a measurement is added to the measurement list, the memory
would be allocated/freed.  The frequency of new measurements is policy
dependent.  For performance reasons, I'd prefer if the allocation
remains on the stack.

Mimi