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

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Message-ID: <thza4ufhxxdy5lggglgqkzjtokl6shweszs3cqmdkxlhsg6wcq@6l6jn5samgsu>
Date: Mon, 10 Mar 2025 16:00:09 +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>, 
	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 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!

Thanks,
Stefano

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