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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.
Fixes:
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.. | ||
netfilter | ||
br_arp_nd_proxy.c | ||
br_cfm_netlink.c | ||
br_cfm.c | ||
br_device.c | ||
br_fdb.c | ||
br_forward.c | ||
br_if.c | ||
br_input.c | ||
br_ioctl.c | ||
br_mdb.c | ||
br_mrp_netlink.c | ||
br_mrp_switchdev.c | ||
br_mrp.c | ||
br_mst.c | ||
br_multicast_eht.c | ||
br_multicast.c | ||
br_netfilter_hooks.c | ||
br_netfilter_ipv6.c | ||
br_netlink_tunnel.c | ||
br_netlink.c | ||
br_nf_core.c | ||
br_private_cfm.h | ||
br_private_mcast_eht.h | ||
br_private_mrp.h | ||
br_private_stp.h | ||
br_private_tunnel.h | ||
br_private.h | ||
br_stp_bpdu.c | ||
br_stp_if.c | ||
br_stp_timer.c | ||
br_stp.c | ||
br_switchdev.c | ||
br_sysfs_br.c | ||
br_sysfs_if.c | ||
br_vlan_options.c | ||
br_vlan_tunnel.c | ||
br_vlan.c | ||
br.c | ||
Kconfig | ||
Makefile |