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From: Andrea Parri <parri.andrea@gmail.com>
To: Michael Kelley <mikelley@microsoft.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	KY Srinivasan <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>, Juan Vazquez <juvazq@microsoft.com>,
	Saruhan Karademir <skarade@microsoft.com>
Subject: Re: [PATCH v2 4/7] Drivers: hv: vmbus: Copy the hv_message object in vmbus_on_msg_dpc()
Date: Sun, 6 Dec 2020 22:33:08 +0100	[thread overview]
Message-ID: <20201206213308.GA11423@andrea> (raw)
In-Reply-To: <MW2PR2101MB105225FDDE123AE3A852C665D7CF1@MW2PR2101MB1052.namprd21.prod.outlook.com>

On Sun, Dec 06, 2020 at 06:39:39PM +0000, Michael Kelley wrote:
> From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Wednesday, December 2, 2020 1:22 AM
> > 
> > The hv_message object is in memory shared with the host.  To prevent
> > an erroneous or a malicious host from 'corrupting' such object, copy
> > the object into private memory.

[...]

> But if we're going to just make a copy at the start and use the copy for
> everything, then the motivation for the changes in Patches 2 and 3 goes
> away.  The double-fetch problem is solved entirely by Patch 4.  The
> changes in Patches 2 and 3 *are* nice for simplifying the code, but
> that's all.  The code simplification is still useful as prep to reduce the
> number of references to "msg" that have to be changed to "msg_copy",
> but the commit message should be changed to reflect that, rather than
> to eliminate double fetches.

I'm okay with this: I will revisit the commit messages of 2/3, maybe
squash those 'simplifications' into a single patch, and then 'solve'
/guard against the double fetch problem with 4.

Thanks,
  Andrea

  reply	other threads:[~2020-12-06 21:34 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-02  9:22 [PATCH v2 0/7] Drivers: hv: vmbus: More VMBus-hardening changes Andrea Parri (Microsoft)
2020-12-02  9:22 ` [PATCH v2 1/7] Drivers: hv: vmbus: Initialize memory to be sent to the host Andrea Parri (Microsoft)
2020-12-02  9:22 ` [PATCH v2 2/7] Drivers: hv: vmbus: Avoid double fetch of msgtype in vmbus_on_msg_dpc() Andrea Parri (Microsoft)
2020-12-02 12:22   ` Wei Liu
2020-12-02 13:37     ` Andrea Parri
2020-12-02 13:40       ` Wei Liu
2020-12-02 14:14         ` Andrea Parri
2020-12-02  9:22 ` [PATCH v2 3/7] Drivers: hv: vmbus: Avoid double fetch of payload_size " Andrea Parri (Microsoft)
2020-12-02  9:22 ` [PATCH v2 4/7] Drivers: hv: vmbus: Copy the hv_message object " Andrea Parri (Microsoft)
2020-12-06 18:39   ` Michael Kelley
2020-12-06 21:33     ` Andrea Parri [this message]
2020-12-02  9:22 ` [PATCH v2 5/7] Drivers: hv: vmbus: Avoid use-after-free in vmbus_onoffer_rescind() Andrea Parri (Microsoft)
2020-12-02  9:22 ` [PATCH v2 6/7] Drivers: hv: vmbus: Resolve race condition " Andrea Parri (Microsoft)
2020-12-02  9:22 ` [PATCH v2 7/7] Drivers: hv: vmbus: Do not allow overwriting vmbus_connection.channels[] Andrea Parri (Microsoft)

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