Subject: [PATCH 5.4 01/62] etherdevice: Adjust ether_addr* prototypes to silence -Wstringop-overead

From: Greg Kroah-Hartman <[email-masked]>
Date: Tue, 26 Apr 2022 10:20:41 +0200

From: Kees Cook <[email-masked]>

commit 2618a0dae09ef37728dab89ff60418cbe25ae6bd upstream.

With GCC 12, -Wstringop-overread was warning about an implicit cast from
char[6] to char[8]. However, the extra 2 bytes are always thrown away,
alignment doesn't matter, and the risk of hitting the edge of unallocated
memory has been accepted, so this prototype can just be converted to a
regular char *. Silences:

net/core/dev.c: In function ‘bpf_prog_run_generic_xdp’: net/core/dev.c:4618:21: warning: ‘ether_addr_equal_64bits’ reading 8 bytes from a region of size 6 [-Wstringop-overread]
 4618 |         orig_host = ether_addr_equal_64bits(eth->h_dest, > skb->dev->dev_addr);
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/core/dev.c:4618:21: note: referencing argument 1 of type ‘const u8[8]’ {aka ‘const unsigned char[8]’}
net/core/dev.c:4618:21: note: referencing argument 2 of type ‘const u8[8]’ {aka ‘const unsigned char[8]’}
In file included from net/core/dev.c:91: include/linux/etherdevice.h:375:20: note: in a call to function ‘ether_addr_equal_64bits’
  375 | static inline bool ether_addr_equal_64bits(const u8 addr1[6+2],
      |                    ^~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Marc Kleine-Budde <[email-masked]>
Tested-by: Marc Kleine-Budde <[email-masked]>
Link: https://lore.kernel.org/netdev/[email-masked]
Cc: Jakub Kicinski <[email-masked]>
Cc: "David S. Miller" <[email-masked]>
Cc: [email-masked]
Signed-off-by: Kees Cook <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
Cc: Khem Raj <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
---
 include/linux/etherdevice.h |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -127,7 +127,7 @@ static inline bool is_multicast_ether_ad
 #endif
 }
 
-static inline bool is_multicast_ether_addr_64bits(const u8 addr[6+2])
+static inline bool is_multicast_ether_addr_64bits(const u8 *addr)
 {
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
 #ifdef __BIG_ENDIAN
@@ -341,8 +341,7 @@ static inline bool ether_addr_equal(cons
  * Please note that alignment of addr1 & addr2 are only guaranteed to be 16 bits.
  */
 
-static inline bool ether_addr_equal_64bits(const u8 addr1[6+2],
-					   const u8 addr2[6+2])
+static inline bool ether_addr_equal_64bits(const u8 *addr1, const u8 *addr2)
 {
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
 	u64 fold = (*(const u64 *)addr1) ^ (*(const u64 *)addr2);