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

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Message-ID: <d7xxfu4af2wafmlj73ffhvmncg6zfuhc5cacezijddshbgmicx@37acg47rvclu>
Date: Mon, 10 Mar 2025 15:57:08 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
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 Fri, Mar 07, 2025 at 05:00:08PM +0100, Michal Luczaj wrote:
>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?

I usually use --nogit so I put in CC pretty much just what's in 
MAINTAINERS (there I hope there are no bouncing addresses).

Thanks,
Stefano

>
>> 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?
>