Messages in this thread | | | Date | Sat, 13 Feb 2016 10:00:56 +0100 | Subject | Re: [kernel-hardening] [PATCH] arm64: vdso: Mark vDSO code as read-only | From | Ard Biesheuvel <> |
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On 13 February 2016 at 01:31, David Brown <david.brown@linaro.org> wrote: > On Thu, Feb 11, 2016 at 03:19:20PM +0100, Ard Biesheuvel wrote: > >>> diff --git a/arch/arm64/kernel/vdso/vdso.S >>> b/arch/arm64/kernel/vdso/vdso.S >>> index 60c1db5..db7c0f2 100644 >>> --- a/arch/arm64/kernel/vdso/vdso.S >>> +++ b/arch/arm64/kernel/vdso/vdso.S >>> @@ -24,6 +24,7 @@ >>> __PAGE_ALIGNED_DATA >> >> >> ^^ You can get rid of this now as well > > > Can we? The page is getting mapped to userspace, and if we didn't > page align it, we could leak kernel read-only data to every userspace > process. >
That's what the .balign is for. __PAGE_ALIGNED_DATA only sets the section, and you're overriding that right after.
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