[PATCH AUTOSEL 5.15 29/46] ipv6/sit: use DEV_STATS_INC() to avoid data-races

Sasha Levin
2022-12-18T16:42:36Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit cb34b7cf17ecf33499c9298943f85af247abc1e9 ]

syzbot/KCSAN reported that multiple cpus are updating dev->stats.tx_error
concurrently.

This is because sit tunnels are NETIF_F_LLTX, meaning their ndo_start_xmit()
is not protected by a spinlock.

While original KCSAN report was about tx path, rx path has the same issue.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv6/sit.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 946871741f12..d4cdc2b1b468 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -696,7 +696,7 @@ static int ipip6_rcv(struct sk_buff *skb)
skb->dev = tunnel->dev;

if (packet_is_spoofed(skb, iph, tunnel)) {
- tunnel->dev->stats.rx_errors++;
+ DEV_STATS_INC(tunnel->dev, rx_errors);
goto out;
}

@@ -716,8 +716,8 @@ static int ipip6_rcv(struct sk_buff *skb)
net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
&iph->saddr, iph->tos);
if (err > 1) {
- ++tunnel->dev->stats.rx_frame_errors;
- ++tunnel->dev->stats.rx_errors;
+ DEV_STATS_INC(tunnel->dev, rx_frame_errors);
+ DEV_STATS_INC(tunnel->dev, rx_errors);
goto out;
}
}
@@ -948,7 +948,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
if (!rt) {
rt = ip_route_output_flow(tunnel->net, &fl4, NULL);
if (IS_ERR(rt)) {
- dev->stats.tx_carrier_errors++;
+ DEV_STATS_INC(dev, tx_carrier_errors);
goto tx_error_icmp;
}
dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst, fl4.saddr);
@@ -956,14 +956,14 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,

if (rt->rt_type != RTN_UNICAST) {
ip_rt_put(rt);
- dev->stats.tx_carrier_errors++;
+ DEV_STATS_INC(dev, tx_carrier_errors);
goto tx_error_icmp;
}
tdev = rt->dst.dev;

if (tdev == dev) {
ip_rt_put(rt);
- dev->stats.collisions++;
+ DEV_STATS_INC(dev, collisions);
goto tx_error;
}

@@ -976,7 +976,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
mtu = dst_mtu(&rt->dst) - t_hlen;

if (mtu < IPV4_MIN_MTU) {
- dev->stats.collisions++;
+ DEV_STATS_INC(dev, collisions);
ip_rt_put(rt);
goto tx_error;
}
@@ -1015,7 +1015,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
if (!new_skb) {
ip_rt_put(rt);
- dev->stats.tx_dropped++;
+ DEV_STATS_INC(dev, tx_dropped);
kfree_skb(skb);
return NETDEV_TX_OK;
}
@@ -1045,7 +1045,7 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
dst_link_failure(skb);
tx_error:
kfree_skb(skb);
- dev->stats.tx_errors++;
+ DEV_STATS_INC(dev, tx_errors);
return NETDEV_TX_OK;
}

@@ -1064,7 +1064,7 @@ static netdev_tx_t sit_tunnel_xmit__(struct sk_buff *skb,
return NETDEV_TX_OK;
tx_error:
kfree_skb(skb);
- dev->stats.tx_errors++;
+ DEV_STATS_INC(dev, tx_errors);
return NETDEV_TX_OK;
}

@@ -1093,7 +1093,7 @@ static netdev_tx_t sit_tunnel_xmit(struct sk_buff *skb,
return NETDEV_TX_OK;

tx_err:
- dev->stats.tx_errors++;
+ DEV_STATS_INC(dev, tx_errors);
kfree_skb(skb);
return NETDEV_TX_OK;

--
2.35.1