[PATCH v2 net] bonding: prevent potential infinite loop in bond_header_parse()

[PATCH v2 net] bonding: prevent potential infinite loop in bond_header_parse()

[Eric Dumazet]

bond_header_parse() can loop if a stack of two bonding devices is setup,
because skb->dev always points to the hierarchy top.

Add new "const struct net_device *dev" parameter to
(struct header_ops)->parse() method to make sure the recursion
is bounded, and that the final leaf parse method is called.

Fixes: 950803f72547 ("bonding: fix type confusion in bond_setup_by_slave()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Tested-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Cc: Jay Vosburgh <jv@jvosburgh.net>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
---
v2: removed a dubious kdoc (Jakub)

 drivers/firewire/net.c          | 5 +++--
 drivers/net/bonding/bond_main.c | 8 +++++---
 include/linux/etherdevice.h     | 3 ++-
 include/linux/if_ether.h        | 3 ++-
 include/linux/netdevice.h       | 6 ++++--
 net/ethernet/eth.c              | 9 +++------
 net/ipv4/ip_gre.c               | 3 ++-
 net/mac802154/iface.c           | 4 +++-
 net/phonet/af_phonet.c          | 5 ++++-
 9 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index f1a2bee39bf113fe78f4640ba92a7b4e602c213a..82b3b6d9ed2df6423d5cb7a35282d01775e6cee5 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -257,9 +257,10 @@ static void fwnet_header_cache_update(struct hh_cache *hh,
 	memcpy((u8 *)hh->hh_data + HH_DATA_OFF(FWNET_HLEN), haddr, net->addr_len);
 }
 
-static int fwnet_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+static int fwnet_header_parse(const struct sk_buff *skb, const struct net_device *dev,
+			      unsigned char *haddr)
 {
-	memcpy(haddr, skb->dev->dev_addr, FWNET_ALEN);
+	memcpy(haddr, dev->dev_addr, FWNET_ALEN);
 
 	return FWNET_ALEN;
 }
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 707419270ebf217a71b0593880c7a9a1481b7171..33f414d03ab913c58cf2406a4ab25e611c528159 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1530,9 +1530,11 @@ static int bond_header_create(struct sk_buff *skb, struct net_device *bond_dev,
 	return ret;
 }
 
-static int bond_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+static int bond_header_parse(const struct sk_buff *skb,
+			     const struct net_device *dev,
+			     unsigned char *haddr)
 {
-	struct bonding *bond = netdev_priv(skb->dev);
+	struct bonding *bond = netdev_priv(dev);
 	const struct header_ops *slave_ops;
 	struct slave *slave;
 	int ret = 0;
@@ -1542,7 +1544,7 @@ static int bond_header_parse(const struct sk_buff *skb, unsigned char *haddr)
 	if (slave) {
 		slave_ops = READ_ONCE(slave->dev->header_ops);
 		if (slave_ops && slave_ops->parse)
-			ret = slave_ops->parse(skb, haddr);
+			ret = slave_ops->parse(skb, slave->dev, haddr);
 	}
 	rcu_read_unlock();
 	return ret;
diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 9a1eacf35d37087ba8877bf31c017445929041ed..df8f88f63a7063fbd1df5248d2fc02c859a7bc74 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -42,7 +42,8 @@ extern const struct header_ops eth_header_ops;
 
 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
 	       const void *daddr, const void *saddr, unsigned len);
-int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr);
+int eth_header_parse(const struct sk_buff *skb, const struct net_device *dev,
+		     unsigned char *haddr);
 int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh,
 		     __be16 type);
 void eth_header_cache_update(struct hh_cache *hh, const struct net_device *dev,
diff --git a/include/linux/if_ether.h b/include/linux/if_ether.h
index 61b7335aa037c7232a0caa45572043057c02dde3..ca9afa824aa4faf832658043bda6fb430633e476 100644
--- a/include/linux/if_ether.h
+++ b/include/linux/if_ether.h
@@ -40,7 +40,8 @@ static inline struct ethhdr *inner_eth_hdr(const struct sk_buff *skb)
 	return (struct ethhdr *)skb_inner_mac_header(skb);
 }
 
-int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr);
+int eth_header_parse(const struct sk_buff *skb, const struct net_device *dev,
+		     unsigned char *haddr);
 
 extern ssize_t sysfs_format_mac(char *buf, const unsigned char *addr, int len);
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d7aac6f185bcab8a93a204c349272fc7c1b15ee7..7ca01eb3f7d2b22a188502583dc95121adff7cc9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -311,7 +311,9 @@ struct header_ops {
 	int	(*create) (struct sk_buff *skb, struct net_device *dev,
 			   unsigned short type, const void *daddr,
 			   const void *saddr, unsigned int len);
-	int	(*parse)(const struct sk_buff *skb, unsigned char *haddr);
+	int	(*parse)(const struct sk_buff *skb,
+			 const struct net_device *dev,
+			 unsigned char *haddr);
 	int	(*cache)(const struct neighbour *neigh, struct hh_cache *hh, __be16 type);
 	void	(*cache_update)(struct hh_cache *hh,
 				const struct net_device *dev,
@@ -3445,7 +3447,7 @@ static inline int dev_parse_header(const struct sk_buff *skb,
 
 	if (!dev->header_ops || !dev->header_ops->parse)
 		return 0;
-	return dev->header_ops->parse(skb, haddr);
+	return dev->header_ops->parse(skb, dev, haddr);
 }
 
 static inline __be16 dev_parse_header_protocol(const struct sk_buff *skb)
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 13a63b48b7eeb896dfe98eb0070a261eed2c384b..d9faadbe9b6c86a746cace6d7a7cfffdb84e4519 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -193,14 +193,11 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 }
 EXPORT_SYMBOL(eth_type_trans);
 
-/**
- * eth_header_parse - extract hardware address from packet
- * @skb: packet to extract header from
- * @haddr: destination buffer
- */
-int eth_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+int eth_header_parse(const struct sk_buff *skb, const struct net_device *dev,
+		     unsigned char *haddr)
 {
 	const struct ethhdr *eth = eth_hdr(skb);
+
 	memcpy(haddr, eth->h_source, ETH_ALEN);
 	return ETH_ALEN;
 }
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index e13244729ad8d5b1c2b9c483d25bff0e438134b5..35f0baa99d4092fd499a4795f7f52db33a1fe4e2 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -919,7 +919,8 @@ static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
 	return -(t->hlen + sizeof(*iph));
 }
 
-static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+static int ipgre_header_parse(const struct sk_buff *skb, const struct net_device *dev,
+			      unsigned char *haddr)
 {
 	const struct iphdr *iph = (const struct iphdr *) skb_mac_header(skb);
 	memcpy(haddr, &iph->saddr, 4);
diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
index 9e4631fade90c980887803f313727e9ff943bc73..000be60d9580343e40f33ff872ec0aff7daa41d0 100644
--- a/net/mac802154/iface.c
+++ b/net/mac802154/iface.c
@@ -469,7 +469,9 @@ static int mac802154_header_create(struct sk_buff *skb,
 }
 
 static int
-mac802154_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+mac802154_header_parse(const struct sk_buff *skb,
+		       const struct net_device *dev,
+		       unsigned char *haddr)
 {
 	struct ieee802154_hdr hdr;
 
diff --git a/net/phonet/af_phonet.c b/net/phonet/af_phonet.c
index 238a9638d2b0f6a23070b0871515302d8cba864f..d89225d6bfd3bf7668edf3d0fe563f7bbc97de2c 100644
--- a/net/phonet/af_phonet.c
+++ b/net/phonet/af_phonet.c
@@ -129,9 +129,12 @@ static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
 	return 1;
 }
 
-static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
+static int pn_header_parse(const struct sk_buff *skb,
+			   const struct net_device *dev,
+			   unsigned char *haddr)
 {
 	const u8 *media = skb_mac_header(skb);
+
 	*haddr = *media;
 	return 1;
 }
-- 
2.53.0.851.ga537e3e6e9-goog

Re: [PATCH v2 net] bonding: prevent potential infinite loop in bond_header_parse()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sun, 15 Mar 2026 10:41:52 +0000 you wrote:
> bond_header_parse() can loop if a stack of two bonding devices is setup,
> because skb->dev always points to the hierarchy top.
> 
> Add new "const struct net_device *dev" parameter to
> (struct header_ops)->parse() method to make sure the recursion
> is bounded, and that the final leaf parse method is called.
> 
> [...]

Here is the summary with links:
  - [v2,net] bonding: prevent potential infinite loop in bond_header_parse()
    https://git.kernel.org/netdev/net/c/b7405dcf7385

You are awesome, thank you!
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