CVE-2023-53553

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

HID: hyperv: avoid struct memcpy overrun warning

A previous patch addressed the fortified memcpy warning for most builds, but I still see this one with gcc-9:

In file included from include/linux/string.h:254, from drivers/hid/hid-hyperv.c:8: In function 'fortifymemcpychk', inlined from 'mousevsconreceive' at drivers/hid/hid-hyperv.c:272:3: include/linux/fortify-string.h:583:4: error: call to '_writeoverflowfield' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use structgroup()? [-Werror=attribute-warning] 583 | _writeoverflowfield(psize_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My guess is that the WARN_ON() itself is what confuses gcc, so it no longer sees that there is a correct range check. Rework the code in a way that helps readability and avoids the warning.