netdev - Re: [PATCH net v2 0/6] vsock: Transport reassignment and error handling issues

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Message-ID: <44f050cb-b89d-4c93-ba24-18091dada750@rbox.co>
Date: Wed, 22 Jan 2025 21:10:40 +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>,
 George Zhang <georgezhang@...are.com>, Dmitry Torokhov <dtor@...are.com>,
 Andy King <acking@...are.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net v2 0/6] vsock: Transport reassignment and error
 handling issues

On 1/22/25 16:47, Stefano Garzarella wrote:
> On Wed, 22 Jan 2025 at 15:16, Michal Luczaj <mhal@...x.co> wrote:
>>
>> On 1/22/25 12:45, Stefano Garzarella wrote:
>>> On Tue, Jan 21, 2025 at 03:44:01PM +0100, Michal Luczaj wrote:
>>>> Series deals with two issues:
>>>> - socket reference count imbalance due to an unforgiving transport release
>>>>  (triggered by transport reassignment);
>>>> - unintentional API feature, a failing connect() making the socket
>>>>  impossible to use for any subsequent connect() attempts.
>>>>
>>>> Signed-off-by: Michal Luczaj <mhal@...x.co>
>>>> ---
>>>> Changes in v2:
>>>> - Introduce vsock_connect_fd(), simplify the tests, stick to SOCK_STREAM,
>>>>  collect Reviewed-by (Stefano)
>>>> - Link to v1: https://lore.kernel.org/r/20250117-vsock-transport-vs-autobind-v1-0-c802c803762d@rbox.co
>>>
>>> Thanks for sorting out my comments, I've reviewed it all and got it
>>> running, it seems to be going well!
>>
>> Great! I was worried that I might have oversimplified the UAF selftest
>> (won't trigger the splat if second transport == NULL), so please let me
>> know if it starts acting strangely (quietly passes the test on an unpatched
>> system), and for what combination of enabled transports.
> 
> Yeah, I was worrying the same and thinking if it's better to add more
> connect also with LOOPBACK and a CID > 2 to be sure we test all the
> scenarios, but we can do later, for now let's have this series merged
> to fix the real issue.

Sure, I'll take care of this CID galore later on.

> I tested without the fixes (first 2 patches) and I can see the
> use-after-free reports only on the "host" where I have both loopback
> and H2G loaded, but this should be fine.

Argh, sorry. FWIW, re-adding a bind() after the second connect should
increase the coverage.