From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: David Brown <david.brown@linaro.org>
Cc: kernel-hardening@lists.openwall.com,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>
Subject: Re: [kernel-hardening] [PATCH] arm64: vdso: Mark vDSO code as read-only
Date: Sat, 13 Feb 2016 10:00:56 +0100 [thread overview]
Message-ID: <CAKv+Gu-5OdN7C_SvDytsoSn2QFkVZmonv2ffjpiuEXJA8tc0GA@mail.gmail.com> (raw)
In-Reply-To: <20160213003147.GA12074@davidb.org>
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.
WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [kernel-hardening] [PATCH] arm64: vdso: Mark vDSO code as read-only
Date: Sat, 13 Feb 2016 10:00:56 +0100 [thread overview]
Message-ID: <CAKv+Gu-5OdN7C_SvDytsoSn2QFkVZmonv2ffjpiuEXJA8tc0GA@mail.gmail.com> (raw)
In-Reply-To: <20160213003147.GA12074@davidb.org>
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.
next prev parent reply other threads:[~2016-02-13 9:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 21:52 [PATCH] arm64: vdso: Mark vDSO code as read-only David Brown
2016-02-10 21:52 ` [kernel-hardening] " David Brown
2016-02-10 21:52 ` David Brown
2016-02-11 13:47 ` Will Deacon
2016-02-11 13:47 ` [kernel-hardening] " Will Deacon
2016-02-11 13:47 ` Will Deacon
2016-02-11 14:19 ` [kernel-hardening] " Ard Biesheuvel
2016-02-11 14:19 ` Ard Biesheuvel
2016-02-11 14:19 ` Ard Biesheuvel
2016-02-13 0:31 ` David Brown
2016-02-13 0:31 ` David Brown
2016-02-13 0:31 ` David Brown
2016-02-13 9:00 ` Ard Biesheuvel [this message]
2016-02-13 9:00 ` Ard Biesheuvel
2016-02-13 9:00 ` Ard Biesheuvel
2016-02-16 18:22 ` Catalin Marinas
2016-02-16 18:22 ` [kernel-hardening] " Catalin Marinas
2016-02-16 18:22 ` Catalin Marinas
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