Subject: Re: [PATCH net 2/2] sock: redo the psock vs ULP protection check

From: Jakub Sitnicki <[email-masked]>
Date: Wed, 22 Jun 2022 19:24:16 +0200

On Mon, Jun 20, 2022 at 12:13 PM -07, Jakub Kicinski wrote:
> Commit 8a59f9d1e3d4 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
> has moved the inet_csk_has_ulp(sk) check from sk_psock_init() to
> the new tcp_bpf_update_proto() function. I'm guessing that this
> was done to allow creating psocks for non-inet sockets.
>
> Unfortunately the destruction path for psock includes the ULP
> unwind, so we need to fail the sk_psock_init() itself.
> Otherwise if ULP is already present we'll notice that later,
> and call tcp_update_ulp() with the sk_proto of the ULP
> itself, which will most likely result in the ULP looping
> its callbacks.
>
> Fixes: 8a59f9d1e3d4 ("sock: Introduce sk->sk_prot->psock_update_sk_prot()")
> Signed-off-by: Jakub Kicinski <[email-masked]>
> ---

I followed up with a regression test, if you would like to pick it up
through net tree.

Reviewed-by: Jakub Sitnicki <[email-masked]>
Tested-by: Jakub Sitnicki <[email-masked]>