On Tue, Dec 5, 2023 at 5:40 PM Jann Horn <jannh@xxxxxxxxxx> wrote: > > Hi! > > I think this code is racy, but testing that seems like a pain... > > owner_mt() in xt_owner runs in context of a NF_INET_LOCAL_OUT or > NF_INET_POST_ROUTING hook. It first checks that sk->sk_socket is > non-NULL, then checks that sk->sk_socket->file is non-NULL, then > accesses the ->f_cred of that file. > > I don't see anything that protects this against a concurrent > sock_orphan(), which NULLs out the sk->sk_socket pointer, if we're in Ah, and all the other users of ->sk_socket in net/netfilter/ do it under the sk_callback_lock... so I guess the fix would be to add the same in owner_mt?
