On Thu, Sep 21, 2023 at 10:22:54PM +0000, Jitindar Singh, Suraj wrote:
On Thu, 2023-09-21 at 08:13 +0100, Marc Zyngier wrote:
On Wed, 20 Sep 2023 20:27:28 +0100, Suraj Jitindar Singh surajjs@amazon.com wrote:
From: Quentin Perret qperret@google.com
commit 43c1ff8b75011bc3e3e923adf31ba815864a2494 upstream.
Memory regions marked as "no-map" in the host device-tree routinely include TrustZone carev-outs and DMA pools. Although donating such pages to the hypervisor may not breach confidentiality, it could be used to corrupt its state in uncontrollable ways. To prevent this, let's block host-initiated memory transitions targeting "no-map" pages altogether in nVHE protected mode as there should be no valid reason to do this in current operation.
Thankfully, the pKVM EL2 hypervisor has a full copy of the host's list of memblock regions, so we can easily check for the presence of the MEMBLOCK_NOMAP flag on a region containing pages being donated from the host.
Reviewed-by: Philippe Mathieu-Daudé philmd@linaro.org Tested-by: Vincent Donnefort vdonnefort@google.com Signed-off-by: Quentin Perret qperret@google.com Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Marc Zyngier maz@kernel.org Link: https://lore.kernel.org/r/20221110190259.26861-8-will@kernel.org [ bp: clean ]
What is this?
Noting any details about the backport. In this case it was a clean backport.
Signed-off-by: Suraj Jitindar Singh surajjs@amazon.com
What is the rationale for backporting this? It wasn't tagged as Cc: to stable for a reason: pKVM isn't functional upstream, and won't be for the next couple of cycles *at least*.
So at it stands, I'm against such a backport.
The 2 patches were backported to address CVE-2023-21264. This one provides context for the proceeding patch.
I wasn't aware that it's non functional. Does this mean that the code won't be compiled or just that it can't actually be run currently from the upstream codebase?
I guess I'm trying to understand if the conditions of the CVE are a real concern even if it isn't technically functional.
Why do you think the CVE is actually even valid? Who filed it and why?
Remember, CVEs almost never mean anything for the kernel, they are not able to be given out by the kernel security team, and they just don't make any sense for us.
I'll go drop these patches from the stable queues for now, and wait for you all to agree what is happening here.
thanks,
greg k-h