Subject: [kernel-hardening] [PATCH] arm64: vdso: Mark vDSO code as read-only

From: [email-masked] (David Brown)
Date: Fri, 12 Feb 2016 17:31:47 -0700

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.

David