From:   Dexuan Cui <decui@microsoft.com>
To:     Mohammed Gamal <mgamal@redhat.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>,
        "parri.andrea@gmail.com" <parri.andrea@gmail.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "vkuznets@redhat.com" <vkuznets@redhat.com>
Subject: RE: [PATCH] Drivers: vmbus: Check for channel allocation before
 looking up relids
Thread-Topic: [PATCH] Drivers: vmbus: Check for channel allocation before
 looking up relids
Thread-Index: AQHZO7FcvtVZ42Ia+EWsc9sfieb8y67FZwQg
Date:   Wed, 8 Feb 2023 19:02:59 +0000
Message-ID: <SA1PR21MB1335F1074908B3E00DFA21BDBFD89@SA1PR21MB1335.namprd21.prod.outlook.com>
References: <20230208113424.864881-1-mgamal@redhat.com>
In-Reply-To: <20230208113424.864881-1-mgamal@redhat.com>
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> From: Mohammed Gamal <mgamal@redhat.com>
> Sent: Wednesday, February 8, 2023 3:34 AM
>=20
> relid2channel() assumes vmbus channel array to be allocated when called.
> However, if the guest receives a vmbus interrupt during driver initializa=
tion
> before vmbus_connect() is called or if vmbus_connect() fails, the vmbus
> interrupt service routine is called which in turn calls relid2channel()
> and can cause a null pointer dereference.

Before vmbus_connect() is called or if vmbus_connect() fails, there should
be no VMBus channel related interrupts at all, so relid2channel() can't be
called.=20

Can you please share the log or at least the crash call-stack?
I'm curious how the crash can happen.