CVE-2023-54055: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54055 is a memory leak vulnerability in the Linux kernel's RDMA/irdma driver, specifically affecting the handling of PBLE (Page Buffer List Entry) objects. When the irdma kernel module is removed (rmmod), PBLE object memory and associated Segment Descriptors (SDs) are not properly freed, resulting in a kernel memory leak. The vulnerability affects Linux kernel versions starting from the introduction of the irdma driver (around 5.14) up to the patched releases: 5.15.108, 6.1.25, 6.2.12, and 6.3. It was published on December 24, 2025, with an EPSS score of approximately 0.018% (very low), and no CVSS base score has been assigned by ENISA (Feedly, EUVD).

The root cause is a missing cleanup path for PBLE (Page Buffer List Entry) HMC (Host Memory Cache) objects in the irdma RDMA driver (CWE-401: Missing Release of Memory after Effective Lifetime). Unlike other HMC objects that are statically pre-allocated at initialization, PBLE objects and their Segment Descriptors are dynamically allocated during scale-up operations and are expected to persist until function deinitialization. However, IRDMA_HMC_IW_PBLE was not included in the iw_hmc_obj_types[] table, so irdma_del_hmc_objects() never freed them on module removal. The fix adds IRDMA_HMC_IW_PBLE to the cleanup table while skipping PBLE creation in irdma_create_hmc_obj() to preserve the existing dynamic allocation behavior (Feedly, Kernel Patch 1).

The primary impact is a kernel memory leak that occurs when the irdma module is unloaded. Over time or across repeated module load/unload cycles, this can degrade system memory availability, potentially leading to resource exhaustion and reduced system stability or availability. Confidentiality and integrity are not directly affected, as this is a resource management flaw rather than a code execution or data exposure vulnerability (Feedly).

The fix has been backported to stable Linux kernel releases: 5.15.108, 6.1.25, 6.2.12, and 6.3. Administrators running systems with the irdma RDMA driver should update to one of these patched kernel versions. The relevant upstream patches are available at the kernel stable tree (Kernel Patch 1, Kernel Patch 2, Kernel Patch 3, Kernel Patch 4). As a temporary workaround, avoiding repeated load/unload cycles of the irdma module can reduce the practical impact of the memory leak.