CVE-2025-68751

A false-positive memory sanitizer (KMSAN) warning was found in the Linux kernel's s390 floating-point unit (FPU) code. The vstl inline assembly instruction writes a variable number of bytes depending on runtime values, but the compiler-generated KMSAN instrumentation incorrectly tracked only 1 byte of the write. This caused spurious "uninitialized value" warnings during normal network operations like ping, though no actual memory safety issue exists.

This is a fix for false-positive KMSAN reports on s390 architecture, not a real security vulnerability. The underlying code was functioning correctly; only the sanitizer instrumentation was inaccurate. This affects only kernel developers running KMSAN-enabled debug builds on s390 systems.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.