CVE-2026-93250

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vxlan: mdb: Fix use-after-free in vxlan_mdb_flush()<br /> <br /> vxlan_mdb_flush() iterates over the MDB entries using<br /> hlist_for_each_entry_safe(), which only tolerates the removal of the<br /> current entry. Contrary to the comment above the loop, the removal of an<br /> entry can trigger the removal of another entry.<br /> <br /> Flushing the remotes of a (*, G) entry also removes the (S, G) entries<br /> that were created for its source list, once they are left without<br /> remotes:<br /> <br /> vxlan_mdb_remotes_flush()<br /> -&gt; vxlan_mdb_remote_del()<br /> -&gt; vxlan_mdb_remote_srcs_del()<br /> -&gt; vxlan_mdb_remote_src_del()<br /> -&gt; vxlan_mdb_remote_src_fwd_del()<br /> -&gt; __vxlan_mdb_del()<br /> -&gt; vxlan_mdb_entry_put()<br /> <br /> Such an entry can be located after the (*, G) entry in the list, as<br /> vxlan_mdb_entry_get() returns an existing entry without moving it to the<br /> head of the list. This order is obtained by adding the (S, G) entry<br /> before the (*, G) entry, the latter with NLM_F_REPLACE, as the addition<br /> of the source otherwise fails with -EEXIST. The (S, G) entry is then the<br /> entry saved by hlist_for_each_entry_safe() and it is freed while the<br /> (*, G) entry is processed. The next iteration calls hlist_del() on it<br /> again, writing LIST_POISON1 to LIST_POISON2 [1].<br /> <br /> Besides device deletion, the flush is also reachable from RTM_DELMDB<br /> with NLM_F_BULK.<br /> <br /> Fix by re-reading the next entry after the remotes were flushed. The<br /> current entry cannot be removed by this flush, as source lists can only<br /> be configured on (*, G) entries and the removed entries are (S, G)<br /> entries. It is therefore still linked and its next pointer reflects the<br /> removals.<br /> <br /> [1]<br /> BUG: KASAN: wild-memory-access in vxlan_mdb_entry_put.part.0+0x328/0x588<br /> Write of size 8 at addr dead000000000122 by task ip/327<br /> <br /> CPU: 3 UID: 1000 PID: 327 Comm: ip Not tainted 7.2.0-rc7 #2 PREEMPT<br /> Call trace:<br /> vxlan_mdb_entry_put.part.0+0x328/0x588<br /> vxlan_mdb_flush+0x1d8/0x25c<br /> vxlan_mdb_fini+0x8c/0x100<br /> vxlan_uninit+0x1c/0x7c<br /> unregister_netdevice_many_notify+0x954/0xd4c<br /> rtnl_dellink+0x210/0x530<br /> rtnetlink_rcv_msg+0x434/0x4d0<br /> netlink_rcv_skb+0xc4/0x204<br /> rtnetlink_rcv+0x18/0x24<br /> netlink_unicast+0x4b8/0x548<br /> netlink_sendmsg+0x29c/0x560<br /> ____sys_sendmsg+0x390/0x3ec<br /> ___sys_sendmsg+0x114/0x188<br /> __sys_sendmsg+0xf0/0x178<br /> __arm64_sys_sendmsg+0x48/0x60<br /> invoke_syscall.constprop.0+0x58/0x180<br /> el0_svc_common.constprop.0+0x74/0x140<br /> do_el0_svc+0x30/0x40<br /> el0_svc+0x38/0x98<br /> el0t_64_sync_handler+0xa0/0xe4<br /> el0t_64_sync+0x198/0x19c