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Commit 1c430a72 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
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net: compare_ether_addr[_64bits]() has no ordering 



Neither compare_ether_addr() nor compare_ether_addr_64bits()
(as it can fall back to the former) have comparison semantics
like memcmp() where the sign of the return value indicates sort
order. We had a bug in the wireless code due to a blind memcmp
replacement because of this.

A cursory look suggests that the wireless bug was the only one
due to this semantic difference.

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6eddcb4c

include/linux/etherdevice.h

+6 −5
Original line number Diff line number Diff line
@@ -159,7 +159,8 @@ static inline void eth_hw_addr_random(struct net_device *dev) 
 * @addr1: Pointer to a six-byte array containing the Ethernet address

 * @addr2: Pointer other six-byte array containing the Ethernet address

 *

 * Compare two ethernet addresses, returns 0 if equal

 * Compare two ethernet addresses, returns 0 if equal, non-zero otherwise.

 * Unlike memcmp(), it doesn't return a value suitable for sorting.

 */

static inline unsigned compare_ether_addr(const u8 *addr1, const u8 *addr2)

{
@@ -184,10 +185,10 @@ static inline unsigned long zap_last_2bytes(unsigned long value) 
 * @addr1: Pointer to an array of 8 bytes

 * @addr2: Pointer to an other array of 8 bytes

 *

 * Compare two ethernet addresses, returns 0 if equal.

 * Same result than "memcmp(addr1, addr2, ETH_ALEN)" but without conditional

 * branches, and possibly long word memory accesses on CPU allowing cheap

 * unaligned memory reads.

 * Compare two ethernet addresses, returns 0 if equal, non-zero otherwise.

 * Unlike memcmp(), it doesn't return a value suitable for sorting.

 * The function doesn't need any conditional branches and possibly uses

 * word memory accesses on CPU allowing cheap unaligned memory reads.

 * arrays = { byte1, byte2, byte3, byte4, byte6, byte7, pad1, pad2}

 *

 * Please note that alignment of addr1 & addr2 is only guaranted to be 16 bits.