Wang Yufen wrote:
> If tcp_bpf_sendmsg is running during a tear down operation, psock may be
> freed.
>
> tcp_bpf_sendmsg()
> tcp_bpf_send_verdict()
> sk_msg_return()
> tcp_bpf_sendmsg_redir()
> unlikely(!psock))
> sk_msg_free()
>
> The mem of msg has been uncharged in tcp_bpf_send_verdict() by
> sk_msg_return(), so we need to use sk_msg_free_nocharge while psock
> is null.
>
> This issue can cause the following info:
> WARNING: CPU: 0 PID: 2136 at net/ipv4/af_inet.c:155 inet_sock_destruct+0x13c/0x260
> Call Trace:
> <TASK>
> __sk_destruct+0x24/0x1f0
> sk_psock_destroy+0x19b/0x1c0
> process_one_work+0x1b3/0x3c0
> worker_thread+0x30/0x350
> ? process_one_work+0x3c0/0x3c0
> kthread+0xe6/0x110
> ? kthread_complete_and_exit+0x20/0x20
> ret_from_fork+0x22/0x30
> </TASK>
>
> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
> ---
> net/ipv4/tcp_bpf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> index 1f0364e06619..03c037d2a055 100644
> --- a/net/ipv4/tcp_bpf.c
> +++ b/net/ipv4/tcp_bpf.c
> @@ -139,7 +139,7 @@ int tcp_bpf_sendmsg_redir(struct sock *sk, struct sk_msg *msg,
> int ret;
>
> if (unlikely(!psock)) {
> - sk_msg_free(sk, msg);
> + sk_msg_free_nocharge(sk, msg);
> return 0;
> }
> ret = ingress ? bpf_tcp_ingress(sk, psock, msg, bytes, flags) :
Did you consider simply returning an error code here? This would then
trigger the sk_msg_free_nocharge in the error path of __SK_REDIRECT
and would have the side effect of throwing an error up to user space.
This would be a slight change in behavior from user side but would
look the same as an error if the redirect on the socket threw an
error so I think it would be OK.
Thanks,
John
