David Miller found a problem in a wireless driver where I was using
compare_ether_addr() on potentially unaligned data. Document that
compare_ether_addr() is not safe for use everywhere, and add an equivalent
function that works regardless of alignment.
Signed-off-by: Daniel Drake <[EMAIL PROTECTED]>
Index: linux-2.6.24-rc3-git1/include/linux/etherdevice.h
===================================================================
--- linux-2.6.24-rc3-git1.orig/include/linux/etherdevice.h
+++ linux-2.6.24-rc3-git1/include/linux/etherdevice.h
@@ -123,11 +123,13 @@ static inline void random_ether_addr(u8
}
/**
- * compare_ether_addr - Compare two Ethernet addresses
+ * compare_ether_addr - Compare two 16-bit-aligned Ethernet addresses
* @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. Both addresses must
+ * be 16-bit aligned. For unaligned or potentially unaligned address
+ * comparisons, use compare_ether_addr_unaligned() instead.
*/
static inline unsigned compare_ether_addr(const u8 *addr1, const u8 *addr2)
{
@@ -137,6 +139,21 @@ static inline unsigned compare_ether_add
BUILD_BUG_ON(ETH_ALEN != 6);
return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2])) != 0;
}
+
+/**
+ * compare_ether_addr_unaligned - Compare two Ethernet addresses
+ * @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_ether_addr()
+ * is faster than this function, but unless you can ensure alignment you
+ * must use this function instead.
+ */
+static inline unsigned compare_ether_addr_unaligned(const u8 *addr1,
+ const u8 *addr2)
+{
+ return memcmp(addr1, addr2, ETH_ALEN);
+}
#endif /* __KERNEL__ */
#endif /* _LINUX_ETHERDEVICE_H */
-
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