CVE-2023-54073: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54073 is a kernel crash vulnerability in the Linux kernel's TPM (Trusted Platform Module) subsystem, specifically in the hardware random number generator (hwrng) unregistration path. The flaw involves a missing check for !tpm_amd_is_rng_defective() at the hwrng_unregister() call site, which can lead to list corruption and a kernel BUG (null pointer dereference in __list_del_entry_valid). It was published on December 24, 2025, and affects the Linux kernel (CVE Record). No CVSS score has been assigned as of the time of this report (Feedly).

The root cause is a missing conditional guard in the TPM module's cleanup path: when hwrng_unregister() is called without first verifying that the AMD RNG defect check (tpm_amd_is_rng_defective()) is false, the hwrng entry may not have been registered in the first place, leading to an attempt to remove a list entry with a NULL next pointer. This triggers a kernel BUG in lib/list_debug.c (list_del corruption), classified as a use-before-initialization or improper state management issue (CWE-476 / CWE-665). The crash was observed during module unloading (modprobe) on systems with AMD hardware, as shown in the reported kernel trace: list_del corruption, ffff99560d485790->next is NULL followed by kernel BUG at lib/list_debug.c:49 (Feedly). The fix adds the !tpm_amd_is_rng_defective() guard to the hwrng_unregister() call site, mirroring the condition used during registration (kernel.org patch).

Successful triggering of this vulnerability causes a kernel panic (BUG) on affected Linux systems, resulting in a denial of service (system crash). The impact is limited to availability — there is no evidence of confidentiality or integrity compromise. The crash occurs during TPM module unloading on systems with AMD hardware where the RNG defect path is active, meaning it primarily affects systems with specific AMD TPM configurations (Feedly).

Apply the upstream Linux kernel patches that add the !tpm_amd_is_rng_defective() guard to the hwrng_unregister() call site. Multiple stable-branch patches have been issued, referenced at the following kernel.org commits: 0af0a989e747, 8da5ba044ea7, 1408d27f25c7, and bd8621ca1510. Users should update to a patched kernel version provided by their Linux distribution. As a temporary workaround, avoiding unloading the TPM module on affected AMD hardware can prevent the crash (kernel.org patch).