KASAN currently does not instrument atomic operations implemented in assembly. They can lead to silent, undetected memory corruptions. It should. There is a reference patch for this: https://groups.google.com/forum/#!msg/kasan-dev/3r3Wa8C4RHA/yn2M1B3mAQAJ It was even merged once, but then reverted. Need to update and resubmit.
Atomic operations are done in a35353bb9eb19. But we also need to handle bitops as lots of them are in asm.
FTR, here is an old bitops patch: https://lore.kernel.org/patchwork/patch/772571/ Most likely needs to be all redone now, but at least can serve as a base list of what needs to be instrumented.
This can be closed: http://lkml.kernel.org/r/20190613125950.197667-4-elver@google.com Landed in MM: https://ozlabs.org/~akpm/mmots/broken-out/asm-generic-x86-add-bitops-instrumentation-for-kasan.patch
Good