linux-kernel - [PATCH 3.16 261/305] bonding: prevent out of bound accesses

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Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Ding Tianhong" <dingtianhong@...wei.com>,
	"Nikolay Aleksandrov" <nikolay@...ulusnetworks.com>,
	"Dmitry Vyukov" <dvyukov@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	"Eric Dumazet" <edumazet@...gle.com>
Subject: [PATCH 3.16 261/305] bonding: prevent out of bound accesses

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@...gle.com>

commit f87fda00b6ed232a817c655b8d179b48bde8fdbe 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: 815117adaf5b ("bonding: use ether_addr_equal_unaligned for bond addr compare")
Fixes: bb54e58929f3 ("bonding: Verify RX LACPDU has proper dest mac-addr")
Fixes: 885a136c52a8 ("bonding: use compare_ether_addr_64bits() in ALB")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Acked-by: Dmitry Vyukov <dvyukov@...gle.com>
Acked-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Acked-by: Ding Tianhong <dingtianhong@...wei.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16:
 - 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@...adent.org.uk>
---
 drivers/net/bonding/bond_3ad.c | 11 +++++++----
 drivers/net/bonding/bond_alb.c |  7 ++-----
 drivers/net/bonding/bonding.h  |  7 ++++++-
 3 files changed, 15 insertions(+), 10 deletions(-)

--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -95,11 +95,14 @@
 #define MAC_ADDRESS_EQUAL(A, B)	\
 	ether_addr_equal_64bits((const u8 *)A, (const u8 *)B)
 
-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);
@@ -1614,7 +1617,7 @@ static void ad_clear_agg(struct aggregat
 		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;
@@ -1636,7 +1639,7 @@ static void ad_initialize_agg(struct agg
 	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;
 	}
@@ -1671,7 +1674,7 @@ static void ad_initialize_port(struct po
 	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;
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -44,13 +44,10 @@
 
 
 
-#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;
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -41,6 +41,9 @@
 
 #define BOND_DEFAULT_MIIMON	100
 
+#ifndef __long_aligned
+#define __long_aligned __attribute__((aligned((sizeof(long)))))
+#endif
 /*
  * Less bad way to call ioctl from within the kernel; this needs to be
  * done some other way to get the call out of interrupt context.