Re: [PATCH] x86: kmsan: Fix hook for unaligned accesses

[Brian Johannesmeyer]

On Fri, May 24, 2024 at 10:28:05AM +0200, Alexander Potapenko wrote:
> Nice catch! Does it fix any known bugs?

Not that I know of. Based on my cursory testing, it seems that
string_memcpy_fromio() is rarely called with an unaligned `from`, so
this is a bit of an edge case.

On that note: I tried creating a unit test for this, to verify that
an unaligned memcpy_fromio() would yield uninitialized data without the
patch, and would yield initialized data with the patch. However, what I
found is that kmsan_unpoison_memory() seems to always unpoison an entire
4-byte word, even if called with a `size` of less than 4. However, this
issue is somewhat unrelated to the patch at hand, so I'll create a
separate patch to demonstrate what I mean.

Thanks,
Brian