Subject: [PATCH 30/30] sfc: don't read beyond unicast address list

From: Bert Kenward <[email-masked]>
Date: Wed, 12 Jul 2017 17:19:41 +0100

[ Upstream commit c70d68150f71b84cea6997a53493e17bf18a54db ]

If we have more than 32 unicast MAC addresses assigned to an interface
we will read beyond the end of the address table in the driver when
adding filters. The next 256 entries store multicast addresses, so we
will end up attempting to insert duplicate filters, which is mostly
harmless. If we add more than 288 unicast addresses we will then read
past the multicast address table, which is likely to be more exciting.

Fixes: 12fb0da45c9a ("sfc: clean fallbacks between promisc/normal in efx_ef10_filter_sync_rx_mode")
Signed-off-by: Bert Kenward <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 drivers/net/ethernet/sfc/ef10.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index f4aed889b6ce..5a1b9b219a42 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -5033,12 +5033,9 @@ static void efx_ef10_filter_uc_addr_list(struct efx_nic *efx)
 	struct efx_ef10_filter_table *table = efx->filter_state;
 	struct net_device *net_dev = efx->net_dev;
 	struct netdev_hw_addr *uc;
-	int addr_count;
 	unsigned int i;
 
-	addr_count = netdev_uc_count(net_dev);
 	table->uc_promisc = !!(net_dev->flags & IFF_PROMISC);
-	table->dev_uc_count = 1 + addr_count;
 	ether_addr_copy(table->dev_uc_list[0].addr, net_dev->dev_addr);
 	i = 1;
 	netdev_for_each_uc_addr(uc, net_dev) {
@@ -5049,6 +5046,8 @@ static void efx_ef10_filter_uc_addr_list(struct efx_nic *efx)
 		ether_addr_copy(table->dev_uc_list[i].addr, uc->addr);
 		i++;
 	}
+
+	table->dev_uc_count = i;
 }
 
 static void efx_ef10_filter_mc_addr_list(struct efx_nic *efx)
@@ -5056,11 +5055,10 @@ static void efx_ef10_filter_mc_addr_list(struct efx_nic *efx)
 	struct efx_ef10_filter_table *table = efx->filter_state;
 	struct net_device *net_dev = efx->net_dev;
 	struct netdev_hw_addr *mc;
-	unsigned int i, addr_count;
+	unsigned int i;
 
 	table->mc_promisc = !!(net_dev->flags & (IFF_PROMISC | IFF_ALLMULTI));
 
-	addr_count = netdev_mc_count(net_dev);
 	i = 0;
 	netdev_for_each_mc_addr(mc, net_dev) {
 		if (i >= EFX_EF10_FILTER_DEV_MC_MAX) {
-- 
2.13.0