um: virt-pci: Avoid GCC non-NULL warning
authorKees Cook <keescook@chromium.org>
Fri, 2 Dec 2022 00:23:25 +0000 (16:23 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 7 Jan 2023 10:11:52 +0000 (11:11 +0100)
commitd93b6a8a34e1062cf25b31ac4dc94a3d4130faca
tree67c0c2de921c7a3fc4333ca6a55c1612d8970f20
parentf375bcf69f58fd0744c9dfd1b6b891a27301d67b
um: virt-pci: Avoid GCC non-NULL warning

commit bdc77507fecd00ddad2f502f86a48a9ec38f0f84 upstream.

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 <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202211271212.SUZSC9f9-lkp@intel.com
Fixes: ba38961a069b ("um: Enable FORTIFY_SOURCE")
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Xiu Jianfeng <xiujianfeng@huawei.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: linux-um@lists.infradead.org
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/um/drivers/virt-pci.c