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

From: Vlad Efanov
Date: Fri May 26 2023 - 13:00:19 EST

I will rework the patch.

Best regards,


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->sk_dst_pending_confirm = 0;
old_dst = rcu_dereference_protected(sk->sk_dst_cache,
rcu_assign_pointer(sk->sk_dst_cache, 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.