Re: [PATCH] vsock: use sock_error() to consume sk_err after connect timeout

[Stefano Garzarella <sgarzare@redhat.com>]

On Wed, Jul 29, 2026 at 05:46:29PM +0800, Nguyen Dinh Phi [SG] wrote:
>On 28/7/26 16:21, Stefano Garzarella wrote:
>>On Fri, Jul 24, 2026 at 03:34:23PM +0800, Nguyen Dinh Phi [SG] wrote:
>>>On 24/7/26 05:43, Michal Luczaj wrote:
>>>>On 7/23/26 12:26, Nguyen Dinh Phi [SG] wrote:
>>>>>>>>>...
>>>>>>>>>Yeah, we need to handle that part better, I think it's 
>>>>>>>>>a leftover when
>>>>>>>>>we generalized AF_VSOCK to support more transport than vmci.
>>>>>>>
>>>>>>>Speaking of leftovers, I have trouble understanding where 
>>>>>>>does vsock set
>>>>>>>sk_err on listener sockets anyway. If it doesn't, why vsock_accept()
>>>>>>>checks for it?
>>>>>>
>>>>>>I can't also see where it can be set TBH. Should we remove it ?
>>>>>
>>>>>I couldn't find it for listener side too.
>>>>
>>>>Removing sk_err handling from vsock_accept() solves the problem, right?
>>>>
>>>>thanks,
>>>>Michal
>>>
>>>Yes, confirmed, removing sk_err checks from vsock_accept() does 
>>>solve the problem.
>>
>>Okay, so maybe better on going on this direction. WDYT?
>>
>>Stefano
>>
>
>I'm still a bit concerned about how connect() and poll() interact 
>here, even with the sk_err checks removed from vsock_accept().
>
>For example:
>vsock_accept() now lets us reuse a socket whose connect() failed (call 
>it r0) as syzbot reproducer does. After listen(), r0 becomes a 
>listener (sk_state == TCP_LISTEN) and works correctly -- it accepts 
>connections.
>
>But poll() on r0 still marks POLLERR, even though there is no error on 
>that socket at that point.
>
>As I understand it, sk_err holds an error that has not yet been 
>reported to userspace. In the blocking vsock_connect() case we have 
>already read that error and returned it to the caller, so it is no 
>longer pending
>Shouldn't sk_err be consumed/cleared when vsock_connect() returns it 
>to userspace?

Yeah, makes sense to me, I'll ack the v2.
@Michal WDYT?

As cleanup (separate patch), should we remove the `sk_err` check in 
vsock_accept() ?

Thanks,
Stefano