hsr: hold rcu and dev lock for hsr_get_port_ndev

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: hsr: hold rcu and dev lock for hsr_get_port_ndev hsr_get_port_ndev calls hsr_for_each_port, which need to hold rcu lock. On the other hand, before return the port device, we need to hold the device reference to avoid UaF in the caller function.

References

• https://git.kernel.org/stable/c/9433ba79c2ec3ec7c9a711748701549339c3438c
• https://git.kernel.org/stable/c/68a6729afd3e8e9a2a32538642ce92b96ccf9b1d
• https://git.kernel.org/stable/c/847748fc66d08a89135a74e29362a66ba4e3ab15