linux-kernel - Re: [PATCH AUTOSEL 5.11 50/67] Drivers: hv: vmbus: Initialize memory to be sent to the host

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Date:   Fri, 26 Feb 2021 12:05:53 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Andrea Parri <parri.andrea@...il.com>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Juan Vazquez <juvazq@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, linux-hyperv@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.11 50/67] Drivers: hv: vmbus: Initialize memory
 to be sent to the host

On Wed, Feb 24, 2021 at 02:30:52PM +0100, Andrea Parri wrote:
>On Wed, Feb 24, 2021 at 02:16:00PM +0100, Andrea Parri wrote:
>> On Wed, Feb 24, 2021 at 07:50:08AM -0500, Sasha Levin wrote:
>> > From: "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
>> >
>> > [ Upstream commit e99c4afbee07e9323e9191a20b24d74dbf815bdf ]
>> >
>> > __vmbus_open() and vmbus_teardown_gpadl() do not inizialite the memory
>> > for the vmbus_channel_open_channel and the vmbus_channel_gpadl_teardown
>> > objects they allocate respectively.  These objects contain padding bytes
>> > and fields that are left uninitialized and that are later sent to the
>> > host, potentially leaking guest data.  Zero initialize such fields to
>> > avoid leaking sensitive information to the host.
>> >
>> > Reported-by: Juan Vazquez <juvazq@...rosoft.com>
>> > Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.com>
>> > Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
>> > Link: https://lore.kernel.org/r/20201209070827.29335-2-parri.andrea@gmail.com
>> > Signed-off-by: Wei Liu <wei.liu@...nel.org>
>> > Signed-off-by: Sasha Levin <sashal@...nel.org>
>>
>> Sasha - This patch is one of a group of patches where a Linux guest running on
>> Hyper-V will start assuming that hypervisor behavior might be malicious, and
>> guards against such behavior.  Because this is a new assumption, these patches
>> are more properly treated as new functionality rather than as bug fixes.  So I
>> would propose that we *not* bring such patches back to stable branches.
>
>For future/similar cases: I'm wondering, is there some way to annotate a patch
>with "please do not bring it back"?

There's nothing explicit for the AUTOSEL stuff. A note in the changelog
could work.

-- 
Thanks,
Sasha