From: 163 <freedomsky1986@163.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, linux-hyperv@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Wei Liu <wei.liu@kernel.org>,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"Andrea Parri (Microsoft)" <parri.andrea@gmail.com>
Subject: Re: [EXTERNAL] [PATCH 1/5] Drivers: hv: copy from message page only what's needed
Date: Thu, 2 Apr 2020 22:46:53 +0800 [thread overview]
Message-ID: <3ed15a02-0b86-0ec1-6daf-df94f8fc6ba5@163.com> (raw)
In-Reply-To: <20200401103638.1406431-2-vkuznets@redhat.com>
On 4/1/2020 6:36 PM, Vitaly Kuznetsov wrote:
> Hyper-V Interrupt Message Page (SIMP) has 16 256-byte slots for
> messages. Each message comes with a header (16 bytes) which specifies the
> payload length (up to 240 bytes). vmbus_on_msg_dpc(), however, doesn't
> look at the real message length and copies the whole slot to a temporary
> buffer before passing it to message handlers. This is potentially dangerous
> as hypervisor doesn't have to clean the whole slot when putting a new
> message there and a message handler can get access to some data which
> belongs to a previous message.
>
> Note, this is not currently a problem because all message handlers are
> in-kernel but eventually we may e.g. get this exported to userspace.
>
> Note also, that this is not a performance critical path: messages (unlike
> events) represent rare events so it doesn't really matter (from performance
> point of view) if we copy too much.
>
> Fix the issue by taking into account the real message length. The temporary
> buffer allocated by vmbus_on_msg_dpc() remains fixed size for now.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> drivers/hv/vmbus_drv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 029378c27421..2b5572146358 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1043,7 +1043,8 @@ void vmbus_on_msg_dpc(unsigned long data)
> return;
>
> INIT_WORK(&ctx->work, vmbus_onmessage_work);
> - memcpy(&ctx->msg, msg, sizeof(*msg));
> + memcpy(&ctx->msg, msg, sizeof(msg->header) +
> + msg->header.payload_size);
>
Hi Vitaly:
I think we still need to check whether the payload_size passed from
Hyper-V is valid or not here to avoid cross-border issue before doing
copying.
next prev parent reply other threads:[~2020-04-02 15:03 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 10:36 [PATCH 0/5] Drivers: hv: cleanup VMBus messages handling Vitaly Kuznetsov
2020-04-01 10:36 ` [PATCH 1/5] Drivers: hv: copy from message page only what's needed Vitaly Kuznetsov
2020-04-02 14:46 ` 163 [this message]
2020-04-02 16:26 ` [EXTERNAL] " Vitaly Kuznetsov
2020-04-03 1:52 ` Michael Kelley
2020-04-03 7:03 ` Vitaly Kuznetsov
2020-04-01 10:36 ` [PATCH 2/5] Drivers: hv: allocate the exact needed memory for messages Vitaly Kuznetsov
2020-04-03 1:54 ` Michael Kelley
2020-04-01 10:36 ` [PATCH 3/5] Drivers: hv: avoid passing opaque pointer to vmbus_onmessage() Vitaly Kuznetsov
2020-04-03 1:55 ` Michael Kelley
2020-04-01 10:38 ` [PATCH 4/5] Drivers: hv: make sure that 'struct vmbus_channel_message_header' compiles correctly Vitaly Kuznetsov
2020-04-01 10:38 ` [PATCH 5/5] Drivers: hv: check VMBus messages lengths Vitaly Kuznetsov
2020-04-03 2:00 ` Michael Kelley
2020-04-03 7:07 ` Vitaly Kuznetsov
2020-04-03 1:56 ` [PATCH 4/5] Drivers: hv: make sure that 'struct vmbus_channel_message_header' compiles correctly Michael Kelley
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3ed15a02-0b86-0ec1-6daf-df94f8fc6ba5@163.com \
--to=freedomsky1986@163.com \
--cc=Tianyu.Lan@microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mikelley@microsoft.com \
--cc=parri.andrea@gmail.com \
--cc=sthemmin@microsoft.com \
--cc=vkuznets@redhat.com \
--cc=wei.liu@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).