From: Michael Kelley <mikelley@microsoft.com>
To: "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: RE: [PATCH v2] Drivers: hv: vmbus: Initialize unload_event statically
Date: Tue, 20 Apr 2021 04:50:56 +0000 [thread overview]
Message-ID: <MWHPR21MB15934822FAFFFD4D3FA369BAD7489@MWHPR21MB1593.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20210420014350.2002-1-parri.andrea@gmail.com>
From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Monday, April 19, 2021 6:44 PM
>
> If a malicious or compromised Hyper-V sends a spurious message of type
> CHANNELMSG_UNLOAD_RESPONSE, the function vmbus_unload_response() will
> call complete() on an uninitialized event, and cause an oops.
>
> Reported-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> ---
> Changes since v1[1]:
> - add inline comment in vmbus_unload_response()
>
> [1] https://lore.kernel.org/linux-hyperv/20210416143932.16512-1-parri.andrea@gmail.com/
>
> drivers/hv/channel_mgmt.c | 7 ++++++-
> drivers/hv/connection.c | 2 ++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 4c9e45d1f462c..335a10ee03a5e 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -826,6 +826,11 @@ static void vmbus_unload_response(struct
> vmbus_channel_message_header *hdr)
> /*
> * This is a global event; just wakeup the waiting thread.
> * Once we successfully unload, we can cleanup the monitor state.
> + *
> + * NB. A malicious or compromised Hyper-V could send a spurious
> + * message of type CHANNELMSG_UNLOAD_RESPONSE, and trigger a call
> + * of the complete() below. Make sure that unload_event has been
> + * initialized by the time this complete() is executed.
> */
> complete(&vmbus_connection.unload_event);
> }
> @@ -841,7 +846,7 @@ void vmbus_initiate_unload(bool crash)
> if (vmbus_proto_version < VERSION_WIN8_1)
> return;
>
> - init_completion(&vmbus_connection.unload_event);
> + reinit_completion(&vmbus_connection.unload_event);
> memset(&hdr, 0, sizeof(struct vmbus_channel_message_header));
> hdr.msgtype = CHANNELMSG_UNLOAD;
> vmbus_post_msg(&hdr, sizeof(struct vmbus_channel_message_header),
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index dc19d5ae4373c..311cd005b3be6 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -26,6 +26,8 @@
>
> struct vmbus_connection vmbus_connection = {
> .conn_state = DISCONNECTED,
> + .unload_event = COMPLETION_INITIALIZER(
> + vmbus_connection.unload_event),
> .next_gpadl_handle = ATOMIC_INIT(0xE1E10),
>
> .ready_for_suspend_event = COMPLETION_INITIALIZER(
> --
> 2.25.1
next prev parent reply other threads:[~2021-04-20 4:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 1:43 [PATCH v2] Drivers: hv: vmbus: Initialize unload_event statically Andrea Parri (Microsoft)
2021-04-20 4:50 ` Michael Kelley [this message]
2021-04-20 19:40 ` Wei Liu
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