Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()  vxlan_mdb_is_valid_source(), which validates MDBE_ATTR_SOURCE and every MDBE_ATTR_SRC_LIST member, accepts the all-zeros address.  A source list is only accepted on a (*, G) entry, whose source is the all-zeros address, and for each member of the list an (S, G) entry is derived from it by substituting the source. Entries are keyed by a plain memcmp() of struct vxlan_mdb_entry_key, so if MDBE_ATTR_SOURCE is present and holds the all-zeros address and the source list holds it as well, the derived (S, G) key is byte-identical to the (*, G) key and resolves to the same entry. Omitting MDBE_ATTR_SOURCE is not equivalent, as the key is then left with a zero address family.  vxlan_mdb_remote_src_del() removes the forwarding entry of a source before freeing the source entry:  	vxlan_mdb_remote_src_fwd_del(vxlan, group, remote, &ent->addr); 	vxlan_mdb_remote_src_entry_del(ent);  With the keys aliased, the first call deletes the remote of the entry that owns 'ent' instead of a separate (S, G) entry, and frees 'ent'. The second call then runs on the freed entry, and its hlist_del() reads ->pprev and ->next out of it and writes through them.  Adding the (*, G) entry with NLM_F_REPLACE and no source list marks the all-zeros source for deletion and reaches this from the sweep at the end of vxlan_mdb_remote_srcs_replace().    BUG: KASAN: slab-use-after-free in __vxlan_mdb_add+0x1cd/0xd70   Read of size 8 at addr ffff888102852500 by task poc/84    __vxlan_mdb_add+0x1cd/0xd70    vxlan_mdb_add+0xc0/0x140    rtnl_mdb_add+0x157/0x2a0    rtnetlink_rcv_msg+0x207/0x5a0   Allocated by task 84:    __kmalloc_cache_noprof+0x153/0x360    vxlan_mdb_remote_srcs_add+0x2eb/0x440    __vxlan_mdb_add+0x803/0xd70   Freed by task 84:    kfree+0x14c/0x3b0    vxlan_mdb_remote_del+0x129/0x1a0    __vxlan_mdb_del+0x4f/0xe0    vxlan_mdb_remote_src_fwd_del.isra.0+0x162/0x1b0    __vxlan_mdb_add+0x1c5/0xd70  The MDB operations are netns-scoped, so an unprivileged user can perform them in a new user and network namespace.  Reject the all-zeros address in vxlan_mdb_is_valid_source(), which covers both call sites. A (*, G) entry is expressed by omitting the source, so nothing legitimate is refused.  Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Data source: kernel.org (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

CVEs

• CVE-2026-98122