| From | Kees Cook <> | Date | Mon, 23 Apr 2018 10:06:20 -0700 | Subject | Re: [PATCH 27/37] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text() |
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On Mon, Apr 23, 2018 at 8:47 AM, Joerg Roedel <joro@8bytes.org> wrote: > From: Joerg Roedel <jroedel@suse.de> > > Mapping the kernel text area to user-space makes only sense > if it has the same permissions as in the kernel page-table. > If permissions are different this will cause a TLB reload > when using the kernel page-table, which is as good as not > mapping it at all. > > On 64-bit kernels this patch makes no difference, as the > whole range cloned by pti_clone_kernel_text() is mapped RO > anyway. On 32 bit there are writeable mappings in the range, > so just keep the permissions as they are.
Why are there R/W text mappings in this range? I find that to be unexpected. Shouldn't CONFIG_DEBUG_WX already complain if that were true?
-Kees
-- Kees Cook Pixel Security
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