[rarudduck]

Azure's response: https://azure.microsoft.com/en-us/blog/securing-azure-custom...

This part is interesting considering the performance concerns:

"The majority of Azure customers should not see a noticeable performance impact with this update. We’ve worked to optimize the CPU and disk I/O path and are not seeing noticeable performance impact after the fix has been applied. A small set of customers may experience some networking performance impact. This can be addressed by turning on Azure Accelerated Networking (Windows, Linux), which is a free capability available to all Azure customers."

[boulos]

Disclosure: I work on Google Cloud.

If you run a multitenant workload on a linux system (say you're a PaaS or even just hosting a bunch of WordPress side by side) you should update your kernel as soon as is reasonable. While VM to VM attacks are patched, I'm sure lots of folks are running untrusted code side by side and need to self patch. This is why our docs point this out for say GKE: we can't be sure you're running single tenant, so we're not promising you there's no work to do. Update your OSes people!

[mike_hearn]

No offence intended as I'm sure it's a bit of a madhouse there right now, but is your statement really correct? I read the Spectre paper quite carefully and it appears to be unpatchable. Although the Meltdown paper is the one that conclusively demonstrated user->kernel and vm->vm reads with a PoC, and Spectre "only" demonstrated user->user reads, the Spectre paper clearly shows that any read type should be possible as long as the right sort of gadgets can be found. There seems no particular reason why cross-VM reads shouldn't be possible using the Spectre techniques and the paper says as much here:

For example, if a processor prevents speculative execution of instructions in user processes from accessing kernel memory, the attack will still work.

and

Kernel mode testing has not been performed, but the combination of address truncation/hashing in the history matching and trainability via jumps to illegal destinations suggest that attacks against kernel mode may be possible. The effect on other kinds of jumps, such as interrupts and interrupt returns, is also unknown

There doesn't seem to be any reason to believe VM to VM attacks are either patched nor patchable.

My question to you, which I realise you may be unable to answer - how much does truly dedicated hardware on GCE cost? No co-tenants at all except maybe Google controlled code. Do you even offer it at all? I wasn't able to find much discussion based on a 10 second search.

[boulos]

Sorry for the confusion.

I have been most focused on people being concerned that a neighboring VM could suddenly be an attacker. You're right that the same kind of thing that affects your JavaScript engine as a user affects say Apache or anything that allows requests from external sources. However, that situation already has a much larger attack surface and people in that space should be updating themselves whenever there's any CVE like this.

My concern was that the Azure announcement made it sound like they've done the work, so nothing is required. That's not strictly true, even though providers have mitigated one set of attacks at the host kernel layer, so I wanted to correct that.

[rarudduck]

I'm not sure about GCE but in Azure often the largest node size in a particular family (i.e. D15_v2, G5, M128, etc.) is isolated / dedicated to a single customer.

[willsr]

Interesting that they left it this late.

[boulos]

Disclosure: I work on Google Cloud.

Like the AWS reboots, people will notice. So in the interest of the embargo, both Azure and AWS waited to update as late as they felt was safe. Since we do live migrations and host kernel updates all the time, nobody noticed us :).