oss-security - Re: Linux kernel: powerpc: RTAS calls can be used to compromise kernel integrity

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Date: Thu, 10 Dec 2020 23:47:30 +1100
From: Andrew Donnellan <ajd@...ux.ibm.com>
To: oss-security@...ts.openwall.com,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Cc: Tyrel Datwyler <tyreld@...ux.ibm.com>
Subject: Re: Linux kernel: powerpc: RTAS calls can be used to compromise
 kernel integrity

On 24/11/20 1:41 am, Andrew Donnellan wrote:
> On 9/10/20 12:20 pm, Andrew Donnellan wrote:
>> The Linux kernel for powerpc has an issue with the Run-Time 
>> Abstraction Services (RTAS) interface, allowing root (or CAP_SYS_ADMIN 
>> users) in a VM to overwrite some parts of memory, including kernel 
>> memory.
>>
>> This issue impacts guests running on top of PowerVM or KVM hypervisors 
>> (pseries platform), and does *not* impact bare-metal machines (powernv 
>> platform).
> CVE-2020-27777 has been assigned.

A minor regression has been identified, affecting the ibm,open-errinjct 
RTAS call.

A patch is available at 
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20201208195434.8289-1-tyreld@linux.ibm.com/

Thanks to Tyrel Datwyler for identifying and fixing this issue.

-- 
Andrew Donnellan              OzLabs, ADL Canberra
ajd@...ux.ibm.com             IBM Australia Limited

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