Messages in this thread | | | Date | Tue, 31 May 2022 11:06:07 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v2 6/8] KVM: x86: Bug the VM if the emulator accesses a non-existent GPR |
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On Thu, May 26, 2022 at 09:08:15PM +0000, Sean Christopherson wrote: > Bug the VM, i.e. kill it, if the emulator accesses a non-existent GPR, > i.e. generates an out-of-bounds GPR index. Continuing on all but > gaurantees some form of data corruption in the guest, e.g. even if KVM > were to redirect to a dummy register, KVM would be incorrectly read zeros > and drop writes. > > Note, bugging the VM doesn't completely prevent data corruption, e.g. the > current round of emulation will complete before the vCPU bails out to > userspace. But, the very act of killing the guest can also cause data > corruption, e.g. due to lack of file writeback before termination, so > taking on additional complexity to cleanly bail out of the emulator isn't > justified, the goal is purely to stem the bleeding and alert userspace > that something has gone horribly wrong, i.e. to avoid _silent_ data > corruption. > > Signed-off-by: Sean Christopherson <seanjc@google.com>
I like this -- this ends up failing in a relatively clean fashion. (i.e. it's not actually a BUG(), but rather tells the VM to stop.)
Reviewed-by: Kees Cook <keescook@chromium.org>
-- Kees Cook
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