CVE-2024-35839

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: replace physindev with physinif in nf_bridge_info An skb can be added to a neigh->arp_queue while waiting for an arp reply. Where original skb's skb->dev can be different to neigh's neigh->dev. For instance in case of bridging dnated skb from one veth to another, the skb would be added to a neigh->arp_queue of the bridge. As skb->dev can be reset back to nf_bridge->physindev and used, and as there is no explicit mechanism that prevents this physindev from been freed under us (for instance neigh_flush_dev doesn't cleanup skbs from different device's neigh queue) we can crash on e.g. this stack: arp_process neigh_update skb = __skb_dequeue(&neigh->arp_queue) neigh_resolve_output(..., skb) ... br_nf_dev_xmit br_nf_pre_routing_finish_bridge_slow skb->dev = nf_bridge->physindev br_handle_frame_finish Let's use plain ifindex instead of net_device link. To peek into the original net_device we will use dev_get_by_index_rcu(). Thus either we get device and are safe to use it or we don't get it and drop skb.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

References

• https://git.kernel.org/stable/c/7ae19ee81ca56b13c50a78de6c47d5b8fdc9d97b ↗
• https://git.kernel.org/stable/c/9325e3188a9cf3f69fc6f32af59844bbc5b90547 ↗
• https://git.kernel.org/stable/c/544add1f1cfb78c3dfa3e6edcf4668f6be5e730c ↗
• https://git.kernel.org/stable/c/9874808878d9eed407e3977fd11fee49de1e1d86 ↗