Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 3 Feb 2021 17:23:13 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 06/11] x86/fault: Improve kernel-executing-user-memory handling |
| |
On Sun, Jan 31, 2021 at 09:24:37AM -0800, Andy Lutomirski wrote: > Right now we treat the case of the kernel trying to execute from user > memory more or less just like the kernel getting a page fault on a user > access. In the failure path, we check for erratum #93, try to otherwise > fix up the error, and then oops. > > If we manage to jump to the user address space, with or without SMEP, we > should not try to resolve the page fault. This is an error, pure and > simple. Rearrange the code so that we catch this case early, check for > erratum #93, and bail out.
And I'm scratching my head why are you talking about kernel trying to execute from user memory but doh, that erratum truncates the high 32-bits of rIP and the #PF address looks like a user address but X86_PF_USER is clear.
Aha.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| ![\](/images/icornerr.gif) |