netdev - Re: [PATCH net] vsock/bpf: Handle EINTR connect() racing against sockmap update

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Message-ID: <20250311153803.fuamcj652omyx33j@gmail.com>
Date: Tue, 11 Mar 2025 08:38:03 -0700
From: John Fastabend <john.fastabend@...il.com>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: Michal Luczaj <mhal@...x.co>, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Bobby Eshleman <bobby.eshleman@...edance.com>,
	"Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH net] vsock/bpf: Handle EINTR connect() racing against
 sockmap update

On 2025-03-10 16:00:09, Stefano Garzarella wrote:
> On Mon, Mar 10, 2025 at 12:42:28AM +0100, Michal Luczaj wrote:
> > On 3/7/25 10:27, Michal Luczaj wrote:
> > > Signal delivered during connect() may result in a disconnect of an already
> > > TCP_ESTABLISHED socket. Problem is that such established socket might have
> > > been placed in a sockmap before the connection was closed. We end up with a
> > > SS_UNCONNECTED vsock in a sockmap. And this, combined with the ability to
> > > reassign (unconnected) vsock's transport to NULL, breaks the sockmap
> > > contract. As manifested by WARN_ON_ONCE.
> > > 
> > > Ensure the socket does not stay in sockmap.
> > > 
> > > WARNING: CPU: 10 PID: 1310 at net/vmw_vsock/vsock_bpf.c:90 vsock_bpf_recvmsg+0xb4b/0xdf0
> > > CPU: 10 UID: 0 PID: 1310 Comm: a.out Tainted: G        W          6.14.0-rc4+
> > >  sock_recvmsg+0x1b2/0x220
> > >  __sys_recvfrom+0x190/0x270
> > >  __x64_sys_recvfrom+0xdc/0x1b0
> > >  do_syscall_64+0x93/0x1b0
> > >  entry_SYSCALL_64_after_hwframe+0x76/0x7e
> > > 
> > > Fixes: 634f1a7110b4 ("vsock: support sockmap")
> > > Signed-off-by: Michal Luczaj <mhal@...x.co>
> > 
> > This fix is insufficient; warning can be triggered another way. Apologies.
> 
> No need to apologize, you are doing a great job to improve vsock with bpf!

+1 thanks for working on it! I was out Monday but will catch up with
patches as well.

> 
> Thanks,
> Stefano
> 
> > 
> > maintainer-netdev.rst says author can do that, so:
> > pw-bot: cr
> > 
> 
>