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

[Michal Hocko]

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