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

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Message-ID: <96121a41-20b4-4659-84d1-281b2b1ad710@rbox.co>
Date: Fri, 7 Mar 2025 17:00:08 +0100
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: "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>,
 "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 3/7/25 15:33, Stefano Garzarella wrote:
> On Fri, Mar 07, 2025 at 10:27:50AM +0100, 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>
>> ---
>> net/vmw_vsock/af_vsock.c  | 10 +++++++++-
>> net/vmw_vsock/vsock_bpf.c |  1 +
>> 2 files changed, 10 insertions(+), 1 deletion(-)
> 
> I can't see this patch on the virtualization ML, are you using 
> get_maintainer.pl?

My bad, sorry. In fact, what's the acceptable strategy for bouncing addresses?

> BTW the patch LGTM, thanks for the fix!
> 
> Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

Thanks!

One question for BPF maintainers: sock_map_unhash() does _not_ call
`sk_psock_stop(psock)` nor `cancel_delayed_work_sync(&psock->work)`. Is
this intended?