Messages in this thread | | | Date | Mon, 6 Mar 2023 14:10:17 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v7 24/41] mm: Don't allow write GUPs to shadow stack memory |
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On Mon, Feb 27, 2023 at 02:29:40PM -0800, Rick Edgecombe wrote: > The x86 Control-flow Enforcement Technology (CET) feature includes a new > type of memory called shadow stack. This shadow stack memory has some > unusual properties, which requires some core mm changes to function > properly. > > Shadow stack memory is writable only in very specific, controlled ways. > However, since it is writable, the kernel treats it as such. As a result ^ ,
> there remain many ways for userspace to trigger the kernel to write to > shadow stack's via get_user_pages(, FOLL_WRITE) operations. To make this a
"stacks"
or "to write to a shadow stack via..."
> little less exposed, block writable GUPs for shadow stack VMAs.
GUPs?
I supposed this means "prevent get_user_pages() from pinning pages to which the corresponding VMA is a shadow stack one."?
Or something like that which is less mm-internal speak...
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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