Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

hung_task: fix warnings caused by unaligned lock pointers

The blocker tracking mechanism assumes that lock pointers are at least 4-byte aligned to use their lower bits for type encoding.

However, as reported by Eero Tamminen, some architectures like m68k only guarantee 2-byte alignment of 32-bit values. This breaks the assumption and causes two related WARN_ON_ONCE checks to trigger.

To fix this, the runtime checks are adjusted to silently ignore any lock that is not 4-byte aligned, effectively disabling the feature in such cases and avoiding the related warnings.

Thanks to Geert Uytterhoeven for bisecting!