ray_cs: Split memcpy() to avoid bounds check warning

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally writing across neighboring fields.

Split memcpy() for each address range to help memcpy() correctly reason
about the bounds checking. Avoids the future warning:

In function 'fortify_memcpy_chk',
    inlined from 'memcpy_toio' at ./include/asm-generic/io.h:1204:2,
    inlined from 'ray_build_header.constprop' at drivers/net/wireless/ray_cs.c:984:3:
./include/linux/fortify-string.h:285:4: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
  285 |    __write_overflow_field(p_size_field, size);
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210819202825.3545692-4-keescook@chromium.org

diff --git a/drivers/net/wireless/ray_cs.c b/drivers/net/wireless/ray_cs.c
index de614ac..0f5009c 100644 (file)
--- a/drivers/net/wireless/ray_cs.c
+++ b/drivers/net/wireless/ray_cs.c
@@ -982,7 +982,9 @@ AP to AP    1       1       dest AP         src AP          dest    source
        if (local->net_type == ADHOC) {
                writeb(0, &ptx->mac.frame_ctl_2);
                memcpy_toio(ptx->mac.addr_1, ((struct ethhdr *)data)->h_dest,
-                           2 * ADDRLEN);
+                           ADDRLEN);
+               memcpy_toio(ptx->mac.addr_2, ((struct ethhdr *)data)->h_source,
+                           ADDRLEN);
                memcpy_toio(ptx->mac.addr_3, local->bss_id, ADDRLEN);
        } else { /* infrastructure */