Re: [PATCH net] net/xen-netback: prevent UAF in xenvif_flush_hash()

From: Paolo Abeni
Date: Tue Aug 27 2024 - 07:21:11 EST


On 8/22/24 20:11, Jeongjun Park wrote:
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

The above wording is confusing, do you mean "kfree_rcu does not exit from "...?

kfree_rcu is called when the rcu grace period ends during the iteration,
UAF occurs when accessing head->next after the entry becomes free.

The loop runs with irq disabled, the RCU critical section extends over it, uninterrupted.

Do you have a splat for the reported UAF?

This does not look the correct solution.

Thanks,

Paolo