Commit 1f73a56f authored by Antoine Tenart's avatar Antoine Tenart Committed by Jakub Kicinski
Browse files

net: vxlan: prevent NULL deref in vxlan_xmit_one 



Neither sock4 nor sock6 pointers are guaranteed to be non-NULL in
vxlan_xmit_one, e.g. if the iface is brought down. This can lead to the
following NULL dereference:

  BUG: kernel NULL pointer dereference, address: 0000000000000010
  Oops: Oops: 0000 [#1] SMP NOPTI
  RIP: 0010:vxlan_xmit_one+0xbb3/0x1580
  Call Trace:
   vxlan_xmit+0x429/0x610
   dev_hard_start_xmit+0x55/0xa0
   __dev_queue_xmit+0x6d0/0x7f0
   ip_finish_output2+0x24b/0x590
   ip_output+0x63/0x110

Mentioned commits changed the code path in vxlan_xmit_one and as a side
effect the sock4/6 pointer validity checks in vxlan(6)_get_route were
lost. Fix this by adding back checks.

Since both commits being fixed were released in the same version (v6.7)
and are strongly related, bundle the fixes in a single commit.

Reported-by: default avatarLiang Li <liali@redhat.com>
Fixes: 6f19b2c1 ("vxlan: use generic function for tunnel IPv4 route lookup")
Fixes: 2aceb896 ("vxlan: use generic function for tunnel IPv6 route lookup")
Cc: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: default avatarAntoine Tenart <atenart@kernel.org>
Reviewed-by: default avatarIdo Schimmel <idosch@nvidia.com>
Tested-by: default avatarIdo Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251126102627.74223-1-atenart@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1e43ebcd

drivers/net/vxlan/vxlan_core.c

+15 −3
Original line number Diff line number Diff line
@@ -2349,7 +2349,7 @@ void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, 
	int addr_family;

	__u8 tos, ttl;

	int ifindex;

	int err;

	int err = 0;

	u32 flags = vxlan->cfg.flags;

	bool use_cache;

	bool udp_sum = false;
@@ -2454,12 +2454,18 @@ void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, 


	rcu_read_lock();

	if (addr_family == AF_INET) {

		struct vxlan_sock *sock4 = rcu_dereference(vxlan->vn4_sock);

		struct vxlan_sock *sock4;

		u16 ipcb_flags = 0;

		struct rtable *rt;

		__be16 df = 0;

		__be32 saddr;



		sock4 = rcu_dereference(vxlan->vn4_sock);

		if (unlikely(!sock4)) {

			reason = SKB_DROP_REASON_DEV_READY;

			goto tx_error;

		}



		if (!ifindex)

			ifindex = sock4->sock->sk->sk_bound_dev_if;
@@ -2534,10 +2540,16 @@ void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, 
				    ipcb_flags);

#if IS_ENABLED(CONFIG_IPV6)

	} else {

		struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock);

		struct vxlan_sock *sock6;

		struct in6_addr saddr;

		u16 ip6cb_flags = 0;



		sock6 = rcu_dereference(vxlan->vn6_sock);

		if (unlikely(!sock6)) {

			reason = SKB_DROP_REASON_DEV_READY;

			goto tx_error;

		}



		if (!ifindex)

			ifindex = sock6->sock->sk->sk_bound_dev_if;