Dell and HP Advise All Their Customers To Not Install Spectre BIOS Updates (bleepingcomputer.com)

An anonymous reader writes: The Spectre and Meltdown mess continues with Dell now recommending their customers to not install the BIOS updates that are supposed to resolve the Spectre (Variant 2) vulnerabilities. These updates have been causing numerous problems for users including performance issues, boot issues, reboot issues, and general system stability. Due to this, Dell EMC has updated its knowledgebase article with a statement advising customers to not install the BIOS update and to potentially rollback to the previous BIOS if their computers are exhibiting "unpredictable system behavior". ZDNet reports that HP too has issued a similar advisory. The computer manufacturer pulled its softpaqs BIOS updates with Intel's patches from its website, and said it would be releasing a BIOS update with a previous version of Intel's microcode on Thursday.

Comments

Lawsuits

[ThisIsNotAName]

Considering how poorly Intel has handled this, I'm looking forward to seeing the legal consequences.

Intel's performance so far seems best described as "clown show." Especially for major, industry-wide patches that they should be sure will fix the problem without introducing crippling problems that are just as bad (or worse) than the original problem.

Re:Spectre cannot be even practically exploited.

[mwvdlee]

To me this sounds not so much like a PR efforts as much as Yet Another Intel Fuck-Up that would require additional PR efforts to spin.
You'll note that the Dell advisory explicitely mentions that the advisory applies to the Intel patches. It doesn't mention problems with patches for other CPU's.
As I read this story, Intel provided BIOS updates for their own CPU's, and those BIOS updates are causing problems.
It just happens to be that this particular fuck-up involves the lesser of the two previous bugs, but doesn't really seem caused by that bug itself.
So I guess this means that for Intel CPU's, both bugs are dangerous.

AMD and ARM are still left with only a single reasonably harmless bug.

Communicating.

[DrYak]

ARM is probably the only one of the chipmakers doing the right thing here. Information is quick, public, to the point and fixes are deployed as soon as they are done. There are performance issues with ARM patches but they are taken as necessary.

They just got lucky to be right most of the time.
(Helps that they use a much simpler RISC architecture : Their engineer have probably less to review until they can give a definite answer about what is exploitable.
They can mass-exclude any ARM core that doesn't do speculative execution at all (e.g.: RaspberryPi) ).

AMD is just ignoring it altogether until they no longer can. Regarding Spectre: near zero chance > microcode and software updates are coming, this you can read in statement on their page.

Mordern CPUs *are* complex, it's not impossible for not everybody in a company to know every single details.

Spectre variant 2 is the perfect exemple :
Variant 2 Spectre works by relying on extremely precise gory detail of the implementation of speculative execution around indirect jumps whose destination isn't even known at execution time
(e.g.: a jumptable whose index depends on a result that isn't computed yet.
e.g: That's one possible form to compile a C/C++ ."switch" block into machine code.
That's also what happens when you need to call the virtual overloaded member function of a C++ object member of an array and you haven't computed the index into the array yet)

The Google demo code relies on the format of the internal data that the branch predictor uses to makes it best guess to where this as of yet unkown destination isn't know.
(Basically, the CPU keeps notes of where it jumped-to most of the times during the past when encountering this point of code.
But the way the CPU write down "this point of code" in it notes is actually imprecise and can lead to confusion.
More or less, it's a hash and Google has found a way to cause a hash collision.
The attacker causes their own attack-program to jump to position A, whenever execution arrives at instruction B.
Then the exploited program reaches a different instruction C, but the CPU is confused and thinks it's again at instruction B, and jumps to position A "out of habit" based on its notes, even if in the exploited program, there's no way this could happen ever (e.g.: there's no "position A" listed in the jump table). )

Should Intel admit that they are vulnerable ? Yes, Google caught them with their pants down on this one.

But, the Intel Xeon exploited by Google demo code certainly works completely differently than any AMD CPU.
So for sure they can guarantee that the exact exploit code won't work for on AMD CPUs
(It would be reasonnable guess, even without speaking to any engineer)

Now: is it definitely impossible to somewhat exploit the jump prediction in a globally similar way ?
Well difficult to exclude.
AMD would need to discuss it at lengths with their engineers experts in branch prediction on their CPU.

So first "nearly-zreo" (Shouldn't not work, but who knows ?)

And then, once AMD manages to get hold eventually of the guy who knows: Oh, shit, it turns out there could be a completely different method that could perhaps be applied to exploit indirect jumps on some recent architectures.
So update the page to tell people to do the updates (while continuing to review with the engineer to try to give an actual answer whether there is actually a viable exploit).

AMD are trying their best, but CPUs are complex stuff, and it's not easy to give a definitive answer fast.