Messages in this thread | | | Subject | Re: [PATCH 7/9] x86/mm: Shadow stack page fault error checking | From | Dave Hansen <> | Date | Thu, 7 Jun 2018 09:56:36 -0700 |
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On 06/07/2018 09:26 AM, Andy Lutomirski wrote: >> >> + /* >> + * Verify X86_PF_SHSTK is within a shadow stack VMA. >> + * It is always an error if there is a shadow stack >> + * fault outside a shadow stack VMA. >> + */ >> + if (error_code & X86_PF_SHSTK) { >> + if (!(vma->vm_flags & VM_SHSTK)) >> + return 1; >> + return 0; >> + } >> + > What, if anything, would go wrong without this change? It seems like > it might be purely an optimization. If so, can you mention that in > the comment?
This is a fine exercise. I'm curious what it does, too.
But, I really like it being explicit in the end. If we depend on implicit behavior, I really worry that someone breaks it accidentally.
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