Re: [PATCH] udp6: Fix race condition in udp6_sendmsg & connect

[Vlad Efanov]

I will rework the patch.

Best regards,

Vlad.


On 26.05.2023 19:47, Eric Dumazet wrote:
> On Fri, May 26, 2023 at 6:41 PM Vlad Efanov <vefanov@xxxxxxxxx> wrote:
> > sk_dst_set() is called by sk_setup_caps().
> >
> > sk_dst_set() replaces dst in socket using xchg() call and we still have
> > two tasks use one socket but expect different dst in sk_dst_cache.
> >
> >
> > __sk_dst_set() is rcu protected, but it checks for socket lock.
> >
> >
> > static inline void
> > __sk_dst_set(struct sock *sk, struct dst_entry *dst)
> > {
> >       struct dst_entry *old_dst;
> >
> >       sk_tx_queue_clear(sk);
> >       sk->sk_dst_pending_confirm = 0;
> >       old_dst = rcu_dereference_protected(sk->sk_dst_cache,
> >                           lockdep_sock_is_held(sk));
> >       rcu_assign_pointer(sk->sk_dst_cache, dst);
> >       dst_release(old_dst);
> > }
> I am quite familiar with this code.
>
> What are you trying to say exactly ?
>
> Please come with a V2 without grabbing the socket lock.