CVE-2022-50322: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50322 is a denial-of-service vulnerability in the Linux kernel's Real-Time Clock (RTC) driver for the MSC313 device, caused by a function prototype mismatch in msc313_rtc_probe(). When Clang's kernel Control Flow Integrity (kCFI, CONFIG_CFI_CLANG) is enabled, the mismatch between clk_disable_unprepare() and the expected callback prototype for devm_add_action_or_reset() triggers a runtime failure, manifesting as a kernel panic or thread termination. Affected Linux kernel versions include 5.16 through 6.0.16 and 6.1 through 6.1.2. It was publicly disclosed on September 15, 2025, and carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat Advisory, Red Hat Bugzilla).

The root cause is a function pointer type mismatch (CWE-704: Incorrect Type Conversion or Cast) in the msc313_rtc_probe() function within the Linux kernel's drivers/rtc/rtc-msc313.c. Specifically, clk_disable_unprepare() was passed directly as a callback to devm_add_action_or_reset(), but its prototype does not match the expected callback signature. When kCFI is active, the kernel validates indirect call targets against their expected prototypes at runtime; a mismatch causes an immediate kernel panic or thread kill. The fix refactors the code to use devm_clk_get_enabled() instead, which properly manages clock lifecycle without the prototype mismatch. This issue was identified via Clang's -Wcast-function-type-strict flag, which is stricter than the standard -Wcast-function-type (Red Hat Bugzilla).

Successful triggering of this vulnerability results in a kernel panic or unexpected thread termination on affected systems, constituting a local denial of service. The impact is limited to availability — there is no confidentiality or integrity impact. The vulnerability only manifests on systems compiled with Clang and kCFI enabled (CONFIG_CFI_CLANG), which narrows the affected population to kernels built with that specific configuration (Red Hat Advisory, Red Hat Bugzilla).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation for CVE-2022-50322. The EPSS score is approximately 0.017% (0.000170), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires local access with low privileges and is further constrained to systems using Clang-compiled kernels with kCFI enabled (Red Hat Advisory).

The Linux kernel maintainers have released patches addressing this vulnerability in versions 6.0.17 and 6.1.3, as well as the 6.2 mainline release. Administrators should upgrade to Linux kernel 6.0.17, 6.1.3, or any later version. As a temporary workaround, disabling Clang's kCFI feature (CONFIG_CFI_CLANG) will prevent the runtime failure, though this reduces kernel security hardening. Patch commits are available in the stable kernel tree (Red Hat Bugzilla, Kernel Patch 1, Kernel Patch 2, Kernel Patch 3).