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

Vulnerability Description

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.

References

• https://git.kernel.org/stable/c/3c4423b0c4b98213b3438e15061e1d08220e6982
• https://git.kernel.org/stable/c/a7f0073fcd12ed7de185ef2c0af9d0fa1ddef22c
• https://git.kernel.org/stable/c/a0465723b8581cad27164c9073fd780904cd22d4
• https://git.kernel.org/stable/c/efcff6ce7467f01f0753609f420333f3f2ceceda
• https://git.kernel.org/stable/c/143edf098b80669d05245b2f2367dd156a83a2c5
• https://git.kernel.org/stable/c/d408889d4b54f5501e4becc4dbbb9065143fbf4e
• https://git.kernel.org/stable/c/54d8639af5568fc41c0e274fc3ec9cf86c59fcbb
• https://git.kernel.org/stable/c/0fa5e94a1811d68fbffa0725efe6d4ca62c03d12