bonding: prevent out of bound accesses

commit f87fda00 upstream.

ether_addr_equal_64bits() requires some care about its arguments,
namely that 8 bytes might be read, even if last 2 byte values are not
used.

KASan detected a violation with null_mac_addr and lacpdu_mcast_addr
in bond_3ad.c

Same problem with mac_bcast[] and mac_v6_allmcast[] in bond_alb.c :
Although the 8-byte alignment was there, KASan would detect out
of bound accesses.

Fixes: 815117ad ("bonding: use ether_addr_equal_unaligned for bond addr compare")
Fixes: bb54e589 ("bonding: Verify RX LACPDU has proper dest mac-addr")
Fixes: 885a136c ("bonding: use compare_ether_addr_64bits() in ALB")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Adjust filename
 - Drop change to bond_params::ad_actor_system
 - Fix one more copy of null_mac_addr to use eth_zero_addr()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/bonding/bond_3ad.c

@@ -93,11 +93,14 @@
 // compare MAC addresses
 #define MAC_ADDRESS_COMPARE(A, B) memcmp(A, B, ETH_ALEN)
 
-static struct mac_addr null_mac_addr = { { 0, 0, 0, 0, 0, 0 } };
+static const u8 null_mac_addr[ETH_ALEN + 2] __long_aligned = {
+	0, 0, 0, 0, 0, 0
+};
 static u16 ad_ticks_per_sec;
 static const int ad_delta_in_ticks = (AD_TIMER_INTERVAL * HZ) / 1000;
 
-static const u8 lacpdu_mcast_addr[ETH_ALEN] = MULTICAST_LACPDU_ADDR;
+static const u8 lacpdu_mcast_addr[ETH_ALEN + 2] __long_aligned =
+	MULTICAST_LACPDU_ADDR;
 
 // ================= main 802.3ad protocol functions ==================
 static int ad_lacpdu_send(struct port *port);
@@ -1627,7 +1630,7 @@ static void ad_clear_agg(struct aggregator *aggregator)
 		aggregator->is_individual = false;
 		aggregator->actor_admin_aggregator_key = 0;
 		aggregator->actor_oper_aggregator_key = 0;
-		aggregator->partner_system = null_mac_addr;
+		eth_zero_addr(aggregator->partner_system.mac_addr_value);
 		aggregator->partner_system_priority = 0;
 		aggregator->partner_oper_aggregator_key = 0;
 		aggregator->receive_state = 0;
@@ -1650,7 +1653,7 @@ static void ad_initialize_agg(struct aggregator *aggregator)
 	if (aggregator) {
 		ad_clear_agg(aggregator);
 
-		aggregator->aggregator_mac_address = null_mac_addr;
+		eth_zero_addr(aggregator->aggregator_mac_address.mac_addr_value);
 		aggregator->aggregator_identifier = 0;
 		aggregator->slave = NULL;
 	}
@@ -1686,7 +1689,7 @@ static void ad_initialize_port(struct port *port, int lacp_fast)
 	if (port) {
 		port->actor_port_number = 1;
 		port->actor_port_priority = 0xff;
-		port->actor_system = null_mac_addr;
+		eth_zero_addr(port->actor_system.mac_addr_value);
 		port->actor_system_priority = 0xffff;
 		port->actor_port_aggregator_identifier = 0;
 		port->ntt = false;

drivers/net/bonding/bond_alb.c

@@ -45,13 +45,10 @@
 
 
 
-#ifndef __long_aligned
-#define __long_aligned __attribute__((aligned((sizeof(long)))))
-#endif
-static const u8 mac_bcast[ETH_ALEN] __long_aligned = {
+static const u8 mac_bcast[ETH_ALEN + 2] __long_aligned = {
 	0xff, 0xff, 0xff, 0xff, 0xff, 0xff
 };
-static const u8 mac_v6_allmcast[ETH_ALEN] __long_aligned = {
+static const u8 mac_v6_allmcast[ETH_ALEN + 2] __long_aligned = {
 	0x33, 0x33, 0x00, 0x00, 0x00, 0x01
 };
 static const int alb_delta_in_ticks = HZ / ALB_TIMER_TICKS_PER_SEC;

drivers/net/bonding/bonding.h

@@ -38,6 +38,9 @@
 	       netif_running(dev)			&& \
 	       netif_carrier_ok(dev))
 
+#ifndef __long_aligned
+#define __long_aligned __attribute__((aligned((sizeof(long)))))
+#endif
 /*
  * Checks whether slave is ready for transmit.
  */