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

[Sasha Levin]

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@xxxxxxxxx>
> > >
> > > [ 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@xxxxxxxxxxxxx>
> > > Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> > > Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> > > Link: https://lore.kernel.org/r/20201209070827.29335-2-parri.andrea@xxxxxxxxx
> > > Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> >
> > 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