um: virt-pci: Avoid GCC non-NULL warning

GCC gets confused about the return value of get_cpu_var() possibly
being NULL, so explicitly test for it before calls to memcpy() and
memset(). Avoids warnings like this:

   arch/um/drivers/virt-pci.c: In function 'um_pci_send_cmd':
   include/linux/fortify-string.h:48:33: warning: argument 1 null where non-null expected [-Wnonnull]
      48 | #define __underlying_memcpy     __builtin_memcpy
         |                                 ^
   include/linux/fortify-string.h:438:9: note: in expansion of macro '__underlying_memcpy'
     438 |         __underlying_##op(p, q, __fortify_size);                        \
         |         ^~~~~~~~~~~~~
   include/linux/fortify-string.h:483:26: note: in expansion of macro '__fortify_memcpy_chk'
     483 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
         |                          ^~~~~~~~~~~~~~~~~~~~
   arch/um/drivers/virt-pci.c:100:9: note: in expansion of macro 'memcpy'
     100 |         memcpy(buf, cmd, cmd_size);
         |         ^~~~~~

While at it, avoid literal "8" and use stored sizeof(buf->data) in
memset() and um_pci_send_cmd().

Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]
Fixes: ba38961a069b ("um: Enable FORTIFY_SOURCE")
Cc: Richard Weinberger <[email protected]>
Cc: Anton Ivanov <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Xiu Jianfeng <[email protected]>
Cc: Vincent Whitchurch <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>

0 files changed, 0 insertions, 0 deletions