Messages in this thread | | | Subject | Re: [PATCH RFC v2 0/6] x86: Disabling PTI in compatibility mode | From | Nadav Amit <> | Date | Thu, 15 Feb 2018 16:25:32 -0800 |
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Dave Hansen <dave.hansen@linux.intel.com> wrote:
> On 02/15/2018 08:35 AM, Nadav Amit wrote: >> I removed the PTI disabling while SMEP is unsupported, although I >> must admit I did not fully understand why it is required. > > Do you mean you don't fully understand how PTI gives SMEP-like behavior > on non-SMEP hardware?
No. I understand how it provide SMEP-like behavior, and I understand the value of SMEP by itself.
However, I do not understand why SMEP-like protection is required to protect processes that run in compatibility-mode from Meltdown/Spectre attacks. As far as I understand, the process should not be able to manipulate the kernel to execute code in the low 4GB.
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