CVE-2024-49936: Use After Free

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

net/xen-netback: prevent UAF in xenvif_flush_hash()

During the list_for_each_entry_rcu iteration call of xenvif_flush_hash, kfree_rcu does not exist inside the rcu read critical section, so if kfree_rcu is called when the rcu grace period ends during the iteration, UAF occurs when accessing head->next after the entry becomes free.

Therefore, to solve this, you need to change it to list_for_each_entry_safe.