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

Michal Hocko
2024-02-26T14:52:14Z

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