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From: ebiederm@xmission.com (Eric W. Biederman)
To: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org, linux-security-module@vger.kernel.org,
 linux-ima-devel@lists.sourceforge.net, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org, Dave Young <dyoung@redhat.com>,
 Vivek Goyal <vgoyal@redhat.com>, Baoquan He <bhe@redhat.com>,
 Michael Ellerman <mpe@ellerman.id.au>,
 Stewart Smith <stewart@linux.vnet.ibm.com>,
 Mimi Zohar <zohar@linux.vnet.ibm.com>,
 Eric Richter <erichte@linux.vnet.ibm.com>,
 Andrew Morton <akpm@linux-foundation.org>,
 Balbir Singh <bsingharora@gmail.com>
References: <1472579105-26296-1-git-send-email-bauerman@linux.vnet.ibm.com>
 <8760q7lswz.fsf@x220.int.ebiederm.org>
Date: Wed, 07 Sep 2016 09:19:40 -0500
In-Reply-To: <8760q7lswz.fsf@x220.int.ebiederm.org> (Eric W. Biederman's
 message of "Wed, 07 Sep 2016 08:51:24 -0500")
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Subject: Re: [PATCH v4 0/5] kexec_file: Add buffer hand-over for the next
 kernel
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ebiederm@xmission.com (Eric W. Biederman) writes:

> Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> writes:
>
>> Hello,
>>
>> The purpose of this new version of the series is to fix a small issue that
>> I found, which is that the kernel doesn't remove the memory reservation
>> for the hand-over buffer it received from the previous kernel in the
>> device tree it sets up for the next kernel. The result is that for each
>> successive kexec, a stale hand-over buffer is left behind, wasting memory.
>>
>> This is fixed by changes to kexec_free_handover_buffer and
>> setup_handover_buffer in patch 2. The other change is to fix checkpatch
>> warnings in the last patch.
>
> This is fundamentally broken.  You do not increase the integrity of a
> system by dropping integrity checks.
>
> No. No. No. No.
>
> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>

To be constructive the way we have handled similiar situations in the
past (hotplu memory) is to call kexec_load again.

Eric