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Date: Fri, 7 Jun 2024 20:26:48 +0800
From: Coiby Xu <coxu@redhat.com>
To: Baoquan He <bhe@redhat.com>
Cc: kexec@lists.infradead.org, Ondrej Kozina <okozina@redhat.com>, 
	Milan Broz <gmazyland@gmail.com>, Thomas Staudt <tstaudt@de.ibm.com>, 
	Daniel P =?utf-8?B?LiBCZXJyYW5nw6k=?= <berrange@redhat.com>, Kairui Song <ryncsn@gmail.com>, 
	Jan Pazdziora <jpazdziora@redhat.com>, Pingfan Liu <kernelfans@gmail.com>, 
	Dave Young <dyoung@redhat.com>, linux-kernel@vger.kernel.org, x86@kernel.org, 
	Dave Hansen <dave.hansen@intel.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, 
	Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH v4 1/7] kexec_file: allow to place kexec_buf randomly
Message-ID: <v23pityqahr6tgkhnfjoloqwhxcef23i6xjvpb23qbql5rq436@3baoli7d5vta>
References: <20240523050451.788754-1-coxu@redhat.com>
 <20240523050451.788754-2-coxu@redhat.com>
 <Zl7FLw+YrFN/blA+@MiWiFi-R3L-srv>
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On Tue, Jun 04, 2024 at 03:41:35PM +0800, Baoquan He wrote:
>On 05/23/24 at 01:04pm, Coiby Xu wrote:
>> Currently, kexec_buf is placed in order which means for the same
>> machine, the info in the kexec_buf is always located at the same
>> position each time the machine is booted. This may cause a risk for
>> sensitive information like LUKS volume key. Now struct kexec_buf has a
>> new field random which indicates it's supposed to be placed in a random
>> position.
>>
>> Suggested-by: Jan Pazdziora <jpazdziora@redhat.com>
>> Signed-off-by: Coiby Xu <coxu@redhat.com>
>> ---
>>  include/linux/kexec.h |  2 ++
>>  kernel/kexec_file.c   | 15 +++++++++++++++
>>  2 files changed, 17 insertions(+)
>>
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index f0e9f8eda7a3..cc81b8a903ab 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
[...]
>> @@ -445,6 +456,8 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
>>
>>  	temp_end = min(end, kbuf->buf_max);
>>  	temp_start = temp_end - kbuf->memsz + 1;
>> +	if (kbuf->random)
>> +		temp_start = kexec_random_start(temp_start, temp_end);
>
>As we discussed before, this need be limited in kdump scope, seems v4
>doesn't include the change.

Yes, v4 was sent mainly for you to review the patches by applying to
latest Linus tree. v5 now include the change.

-- 
Best regards,
Coiby