Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe The sit driver's packet transmission path calls: sit_tunnel_xmit() -> update_or_create_fnhe(), which lead to fnhe_remove_oldest() being called to delete entries exceeding FNHE_RECLAIM_DEPTH+random. The race window is between fnhe_remove_oldest() selecting fnheX for deletion and the subsequent kfree_rcu(). During this time, the concurrent path's __mkroute_output() -> find_exception() can fetch the soon-to-be-deleted fnheX, and rt_bind_exception() then binds it with a new dst using a dst_hold(). When the original fnheX is freed via RCU, the dst reference remains permanently leaked. CPU 0 CPU 1 __mkroute_output() find_exception() [fnheX] update_or_create_fnhe() fnhe_remove_oldest() [fnheX] rt_bind_exception() [bind dst] RCU callback [fnheX freed, dst leak] This issue manifests as a device reference count leak and a warning in dmesg when unregistering the net device: unregister_netdevice: waiting for sitX to become free. Usage count = N Ido Schimmel provided the simple test validation method [1]. The fix clears 'oldest->fnhe_daddr' before calling fnhe_flush_routes(). Since rt_bind_exception() checks this field, setting it to zero prevents the stale fnhe from being reused and bound to a new dst just before it is freed. [1] ip netns add ns1 ip -n ns1 link set dev lo up ip -n ns1 address add 192.0.2.1/32 dev lo ip -n ns1 link add name dummy1 up type dummy ip -n ns1 route add 192.0.2.2/32 dev dummy1 ip -n ns1 link add name gretap1 up arp off type gretap \ local 192.0.2.1 remote 192.0.2.2 ip -n ns1 route add 198.51.0.0/16 dev gretap1 taskset -c 0 ip netns exec ns1 mausezahn gretap1 \ -A 198.51.100.1 -B 198.51.0.0/16 -t udp -p 1000 -c 0 -q & taskset -c 2 ip netns exec ns1 mausezahn gretap1 \ -A 198.51.100.1 -B 198.51.0.0/16 -t udp -p 1000 -c 0 -q & sleep 10 ip netns pids ns1 | xargs kill ip netns del ns1
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected e46e23c289f62ccd8e2230d9ce652072d777ff30 before 69d35c12168f9c59b159ae566f77dfad9f96d7ca; affected 5867e20e1808acd0c832ddea2587e5ee49813874 before 4b7210da22429765d19460d38c30eeca72656282; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before 298f1e0694ab4edb6092d66efed93c4554e6ced1; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before b8a44407bdaf2f0c5505cc7d9fc7d8da90cf9a94; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before 041ab9ca6e80d8f792bb69df28ebf1ef39c06af8; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before b84f083f50ecc736a95091691339a1b363962f0e; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before 0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0; affected 67d6d681e15b578c1725bad8ad079e05d1c48a8e before ac1499fcd40fe06479e9b933347b837ccabc2a40; affected bed8941fbdb72a61f6348c4deb0db69c4de87aca; affected f10ce783bcc4d8ea454563a7d56ae781640e7dcb; affected f484595be6b7ef9d095a32becabb5dae8204fb2a; affected 3e6bd2b583f18da9856fc9741ffa200a74a52cba; affected 5ae06218331f39ec45b5d039aa7cb3ddd4bb8008; affected 4589a12dcf80af31137ef202be1ff4a321707a73; affected 5.4.146 before 5.4.302; affected 5.10.65 before 5.10.247; affected 4.4.284 before 4.5; affected 4.9.283 before 4.10; affected 4.14.247 before 4.15; affected 4.19.207 before 4.20; affected 5.13.17 before 5.14; affected 5.14.4 before 5.15 |
| Linux / Linux | affected 5.15; unaffected 0 before 5.15; unaffected 5.4.302 through 5.4.*; unaffected 5.10.247 through 5.10.*; unaffected 5.15.197 through 5.15.*; unaffected 6.1.159 through 6.1.*; unaffected 6.6.117 through 6.6.*; unaffected 6.12.59 through 6.12.*; unaffected 6.17.9 through 6.17.*; unaffected 6.18 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/69d35c12168f9c59b159ae566f77dfad9f96d7ca
- https://git.kernel.org/stable/c/4b7210da22429765d19460d38c30eeca72656282
- https://git.kernel.org/stable/c/298f1e0694ab4edb6092d66efed93c4554e6ced1
- https://git.kernel.org/stable/c/b8a44407bdaf2f0c5505cc7d9fc7d8da90cf9a94
- https://git.kernel.org/stable/c/041ab9ca6e80d8f792bb69df28ebf1ef39c06af8
- https://git.kernel.org/stable/c/b84f083f50ecc736a95091691339a1b363962f0e
- https://git.kernel.org/stable/c/0fd16ed6dc331636fb2a874c42d2f7d3156f7ff0
- https://git.kernel.org/stable/c/ac1499fcd40fe06479e9b933347b837ccabc2a40
ADP enrichment
No English description supplied.
No references supplied.