Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

xen-netback: defer xenvif_mcast_addr_list_free()

In order for the function to legitimately avoid locking/RCU, it needs to run after all TX/RX processing has finished/stopped: Lookups happen from xenvif_start_xmit(), while adds/removes happen from xenvif_tx_action() (called out of xenvif_poll()).

Move the call out of xenvif_disconnect_data() (the call to the function from connect()'s error path doesn't require any cleaning up there), and put it past the synchronization point in backend_disconnect().

This is XSA-527 / CVE-2026-100081.