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

Vlad Efanov
2023-05-26T17:00:18Z

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@ispras.ru> 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.