Re: [PATCH v2] crypto/caam: Avoid GCC constprop bug warning

[Eric Biggers]

On Thu, Dec 01, 2022 at 05:04:14PM -0800, Kees Cook wrote:
> GCC 12 appears to perform constant propagation incompletely(?) and can
> no longer notice that "len" is always 0 when "data" is NULL. Expand the
> check to avoid warnings about memcpy() having a NULL argument:

Is there a gcc option to turn off the "memcpy with NULL and len=0 is undefined
behavior" thing?  It's basically a bug in the C standard.

Note that the kernel already uses options that make other types of undefined
behavior defined: -fno-strict-overflow, -fno-strict-aliasing, and
-fno-delete-null-pointer-checks.

- Eric