linux-kernel - Re: CVE-2023-52451: powerpc/pseries/memhp: Fix access beyond end of drmem array

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Message-ID: <Zdylmz28rZ-mCeiN@tiehlicka>
Date: Mon, 26 Feb 2024 15:52:11 +0100
From: Michal Hocko <mhocko@...e.com>
To: cve@...nel.org, linux-kernel@...r.kernel.org
Cc: linux-cve-announce@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: CVE-2023-52451: powerpc/pseries/memhp: Fix access beyond end of
 drmem array

On Thu 22-02-24 17:21:58, Greg KH wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> powerpc/pseries/memhp: Fix access beyond end of drmem array
> 
> dlpar_memory_remove_by_index() may access beyond the bounds of the
> drmem lmb array when the LMB lookup fails to match an entry with the
> given DRC index. When the search fails, the cursor is left pointing to
> &drmem_info->lmbs[drmem_info->n_lmbs], which is one element past the
> last valid entry in the array. The debug message at the end of the
> function then dereferences this pointer:
> 
>         pr_debug("Failed to hot-remove memory at %llx\n",
>                  lmb->base_addr);

While this is a reasonable fix and the stable material it is really
unclear to me why it has gained a CVE. Memory hotplug is a privileged
operation. Could you clarify please?

-- 
Michal Hocko
SUSE Labs