CVE-2023-52451 is a vulnerability identified in the Linux kernel specifically affecting the powerpc/pseries architecture's memory hotplug handling code. The flaw exists in the function dlpar_memory_remove_by_index(), which is responsible for removing memory blocks (LMBs) dynamically in a hotplug environment. The vulnerability arises when the function attempts to locate a memory block by its DRC index but fails to find a matching entry in the drmem_info->lmbs array. Instead of properly handling the failure, the code leaves the cursor pointer referencing one element beyond the end of the array, leading to an out-of-bounds access when the code dereferences this pointer to log a debug message. This results in a slab-out-of-bounds read error detected by Kernel Address Sanitizer (KASAN), indicating a potential memory safety violation. The issue is triggered during the hot-remove operation of memory on pseries systems and can cause kernel crashes or undefined behavior due to invalid memory access. The root cause is insufficient boundary checking on the array index used for memory block lookup. The vulnerability was discovered through code inspection and confirmed with KASAN testing. The fix involves adding proper logging for failed lookups and ensuring the pointer is dereferenced only when it points to a valid array entry. This vulnerability affects Linux kernel versions containing the specified commit hashes and is relevant to systems running on IBM Power Systems (pseries) architecture that support dynamic logical partitioning (DLPAR) memory hotplug features.

For European organizations using IBM Power Systems running Linux kernels with the affected versions, this vulnerability poses a risk of kernel instability or crashes during memory hot-remove operations. Such instability can lead to denial of service conditions impacting critical workloads, especially in data centers or enterprise environments relying on dynamic memory management for virtualization or partitioning. Although the vulnerability does not appear to allow privilege escalation or arbitrary code execution directly, the out-of-bounds access could be leveraged in complex attack scenarios to cause system crashes or potentially leak sensitive kernel memory. Organizations in sectors such as finance, telecommunications, and government that utilize Power Systems for high-availability services may experience service disruptions. The threat is limited to environments using the pseries architecture with memory hotplug enabled, which is a niche but important segment in enterprise Linux deployments. Since no known exploits are reported in the wild, the immediate risk is moderate but should not be underestimated given the potential for denial of service and system reliability degradation.

1. Apply the official Linux kernel patches that address CVE-2023-52451 as soon as they become available from trusted sources or Linux distribution vendors. 2. For organizations unable to patch immediately, consider disabling memory hot-remove functionality on affected pseries systems to prevent triggering the vulnerable code path. 3. Monitor kernel logs for messages related to memory hotplug operations and KASAN reports indicating out-of-bounds accesses to detect potential exploitation attempts or system instability. 4. Implement strict change control and testing procedures when performing memory hotplug operations to minimize the risk of triggering the vulnerability in production environments. 5. Engage with hardware and Linux distribution vendors to confirm the presence of the fix in kernel updates and validate system stability post-patching. 6. Maintain up-to-date backups and disaster recovery plans to mitigate impact in case of system crashes caused by this vulnerability.