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net: vxlan: prevent NULL deref in vxlan_xmit_one

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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: Liang Li <liali@redhat.com>
Fixes: 6f19b2c136 ("vxlan: use generic function for tunnel IPv4 route lookup")
Fixes: 2aceb896ee ("vxlan: use generic function for tunnel IPv6 route lookup")
Cc: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251126102627.74223-1-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Antoine Tenart 2025-11-26 11:26:25 +01:00 committed by Jakub Kicinski
parent 1e43ebcd51
commit 1f73a56f98
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/net/vxlan/vxlan_core.c
View File

@ -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;