In the Linux kernel, a rustc compiler bug causes the -Cforce-unwind-tables flag to annotate individual functions but not the entire module. The resulting module constructor lacks the required uwtable annotation. When the CONFIG_UNWIND_PATCH_PAC_INTO_SCS option is enabled on arm64, the kernel’s bootstrap code attempts to patch the constructor with PA‑C instructions based on incorrect DWARF data. This mismatch causes the constructor to be patched improperly, leading to a crash when it is invoked during boot and producing a kernel panic. The fault manifests as a local availability issue that prevents the system from starting.

The flaw affects Linux kernel builds that compile modules with Rust on the arm64 architecture when the -Cforce-unwind-tables flag is active and the CONFIG_UNWIND_PATCH_PAC_INTO_SCS configuration option is enabled. No specific kernel release is cited; any build that satisfies these conditions is vulnerable. The problem originates from the compiler, not from a particular kernel version or module.

There is no CVSS score or EPSS value, and the vulnerability is not listed in the CISA KEV catalog. The risk is tied to the build environment: a corrupted or maliciously crafted Rust module compiled with the buggy flag could cause a boot‑time crash. An attacker would need to influence the kernel build process or supply a compromised kernel module; an existing running system is not directly exploitable. The impact is high for affected builds because a reboot or recovery is required to restore service, but the attack surface is local to the build pipeline.