Re: [PATCH bpf-next v1 1/3] bpf, sockmap: avoid using sk_socket after free

On Thu, Feb 27, 2025 at 03:04:26PM -0800, Martin KaFai Lau wrote:

On 2/26/25 5:22 AM, Jiayuan Chen wrote:

quoted

Use RCU lock to protect sk_socket, preventing concurrent close and release
by another thread.

Because TCP/UDP are already within a relatively large critical section:
'''
ip_local_deliver_finish
   rcu_read_lock
   ip_protocol_deliver_rcu
       tcp_rcv/udp_rcv
   rcu_read_unlock
'''

Adding rcu_read_{un}lock() at the entrance and exit of sk_data_ready
will not increase performance overhead.

Can it use a Fixes tag?

Thanks, Martin.
It seems that this issue has existed since sockmap supported unix.
I'll find the corresponding commit as the Fixes tag.