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Re: [kernel-hardening] [PATCH v5 13/32] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm

From Dave Hansen <dave.hansen@intel.com>
Newsgroups linux.kernel
Subject Re: [kernel-hardening] [PATCH v5 13/32] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm
Date 2016-07-12 20:00 +0200
Message-ID <rUa8q-8da-21@gated-at.bofh.it> (permalink)
References <rTQt3-3Fx-3@gated-at.bofh.it> <rTQt4-3Fx-31@gated-at.bofh.it>
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On 07/11/2016 01:53 PM, Andy Lutomirski wrote:
> If we get a vmalloc fault while current->active_mm->pgd doesn't
> match CR3, we'll crash without this change.  I've seen this failure
> mode on heavily instrumented kernels with virtually mapped stacks.

When does this happen, btw?  Crossing page boundaries on the stack
between the time we swap mm's and the time we switch stacks?

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Thread

[PATCH v5 13/32] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm Andy Lutomirski <luto@kernel.org> - 2016-07-11 23:00 +0200
  Re: [kernel-hardening] [PATCH v5 13/32] x86/mm/64: In  vmalloc_fault(), use CR3 instead of current->active_mm Dave Hansen <dave.hansen@intel.com> - 2016-07-12 20:00 +0200
    Re: [kernel-hardening] [PATCH v5 13/32] x86/mm/64: In  vmalloc_fault(), use CR3 instead of current->active_mm Andy Lutomirski <luto@amacapital.net> - 2016-07-12 20:10 +0200

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