From ed37710d6c672561c3309dab4b86d0f18c8534ff Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 1 Jul 2026 08:22:13 +0000 Subject: [PATCH] macvlan: annotate data-races around vlan->mode and vlan->flags Both fields can be changed in macvlan_changelink() while being read locklessly. Add READ_ONCE()/WRITE_ONCE() annotations. Signed-off-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260701082214.2974946-2-edumazet@google.com Signed-off-by: Paolo Abeni --- drivers/net/macvlan.c | 38 +++++++++++++++++++++----------------- 1 file changed, 21 insertions(+), 17 deletions(-) diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c index c40fa331836b..8b69cc9b70f9 100644 --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -277,7 +277,7 @@ static void macvlan_broadcast(struct sk_buff *skb, return; hash_for_each_rcu(port->vlan_hash, i, vlan, hlist) { - if (vlan->dev == src || !(vlan->mode & mode)) + if (vlan->dev == src || !(READ_ONCE(vlan->mode) & mode)) continue; hash = mc_hash(vlan, eth->h_dest); @@ -306,7 +306,7 @@ static void macvlan_multicast_rx(const struct macvlan_port *port, MACVLAN_MODE_VEPA | MACVLAN_MODE_PASSTHRU| MACVLAN_MODE_BRIDGE); - else if (src->mode == MACVLAN_MODE_VEPA) + else if (READ_ONCE(src->mode) == MACVLAN_MODE_VEPA) /* flood to everyone except source */ macvlan_broadcast(skb, port, src->dev, MACVLAN_MODE_VEPA | @@ -447,7 +447,7 @@ static bool macvlan_forward_source(struct sk_buff *skb, if (!vlan) continue; - if (vlan->flags & MACVLAN_FLAG_NODST) + if (READ_ONCE(vlan->flags) & MACVLAN_FLAG_NODST) consume = true; macvlan_forward_source_one(skb, vlan); } @@ -487,14 +487,18 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb) return RX_HANDLER_CONSUMED; } src = macvlan_hash_lookup(port, eth->h_source); - if (src && src->mode != MACVLAN_MODE_VEPA && - src->mode != MACVLAN_MODE_BRIDGE) { - /* forward to original port. */ - vlan = src; - ret = macvlan_broadcast_one(skb, vlan, eth, 0) ?: - __netif_rx(skb); - handle_res = RX_HANDLER_CONSUMED; - goto out; + if (src) { + enum macvlan_mode mode = READ_ONCE(src->mode); + + if (mode != MACVLAN_MODE_VEPA && + mode != MACVLAN_MODE_BRIDGE) { + /* forward to original port. */ + vlan = src; + ret = macvlan_broadcast_one(skb, vlan, eth, 0) ?: + __netif_rx(skb); + handle_res = RX_HANDLER_CONSUMED; + goto out; + } } hash = mc_hash(NULL, eth->h_dest); @@ -515,7 +519,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb) struct macvlan_dev, list); else vlan = macvlan_hash_lookup(port, eth->h_dest); - if (!vlan || vlan->mode == MACVLAN_MODE_SOURCE) + if (!vlan || READ_ONCE(vlan->mode) == MACVLAN_MODE_SOURCE) return RX_HANDLER_PASS; dev = vlan->dev; @@ -548,7 +552,7 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev) const struct macvlan_port *port = vlan->port; const struct macvlan_dev *dest; - if (vlan->mode == MACVLAN_MODE_BRIDGE) { + if (READ_ONCE(vlan->mode) == MACVLAN_MODE_BRIDGE) { const struct ethhdr *eth = skb_eth_hdr(skb); /* send to other bridge ports directly */ @@ -559,7 +563,7 @@ static int macvlan_queue_xmit(struct sk_buff *skb, struct net_device *dev) } dest = macvlan_hash_lookup(port, eth->h_dest); - if (dest && dest->mode == MACVLAN_MODE_BRIDGE) { + if (dest && READ_ONCE(dest->mode) == MACVLAN_MODE_BRIDGE) { /* send to lowerdev first for its network taps */ dev_forward_skb(vlan->lowerdev, skb); @@ -777,7 +781,7 @@ static int macvlan_set_mac_address(struct net_device *dev, void *p) if (ether_addr_equal(dev->dev_addr, addr->__data)) return 0; - if (vlan->mode == MACVLAN_MODE_PASSTHRU) { + if (READ_ONCE(vlan->mode) == MACVLAN_MODE_PASSTHRU) { macvlan_set_addr_change(vlan->port); return dev_set_mac_address(vlan->lowerdev, addr, NULL); } @@ -1645,7 +1649,7 @@ static int macvlan_changelink(struct net_device *dev, if (err < 0) return err; } - vlan->flags = flags; + WRITE_ONCE(vlan->flags, flags); } if (data && data[IFLA_MACVLAN_BC_QUEUE_LEN]) { @@ -1658,7 +1662,7 @@ static int macvlan_changelink(struct net_device *dev, vlan, nla_get_s32(data[IFLA_MACVLAN_BC_CUTOFF])); if (set_mode) - vlan->mode = mode; + WRITE_ONCE(vlan->mode, mode); if (data && data[IFLA_MACVLAN_MACADDR_MODE]) { if (vlan->mode != MACVLAN_MODE_SOURCE) return -EINVAL;