From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Borislav Petkov <bp@suse.de>,
Fenghua Yu <fenghua.yu@intel.com>,
Yinghai Lu <yinghai@kernel.org>,
Seiji Aguchi <seiji.aguchi@hds.com>,
PaX Team <pageexec@freemail.hu>
Subject: Re: [PATCH] x86: make sure IDT is page aligned
Date: Fri, 12 Jul 2013 15:27:01 -0700 [thread overview]
Message-ID: <51E082B5.4020401@zytor.com> (raw)
In-Reply-To: <20130712183014.GA20551@www.outflux.net>
On 07/12/2013 11:30 AM, Kees Cook wrote:
> Since the IDT is referenced from a fixmap, make sure it is page aligned.
> This avoids the risk of it ever being moved in the bss and having the
> fixmap fail.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Reported-by: PaX Team <pageexec@freemail.hu>
> Cc: stable@vger.kernel.org
> ---
> arch/x86/kernel/head_32.S | 2 +-
> arch/x86/kernel/head_64.S | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
> index e65ddc6..3526dd1 100644
> --- a/arch/x86/kernel/head_32.S
> +++ b/arch/x86/kernel/head_32.S
> @@ -734,7 +734,7 @@ boot_gdt_descr:
> .word __BOOT_DS+7
> .long boot_gdt - __PAGE_OFFSET
>
> - .word 0 # 32-bit align idt_desc.address
> + .word PAGE_SIZE # page align idt_desc.address
> idt_descr:
> .word IDT_ENTRIES*8-1 # idt contains 256 entries
> .long idt_table
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index 5e4d8a8..77e6d3e 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -513,7 +513,7 @@ ENTRY(phys_base)
> #include "../../x86/xen/xen-head.S"
>
> .section .bss, "aw", @nobits
> - .align L1_CACHE_BYTES
> + .align PAGE_SIZE
> ENTRY(idt_table)
> .skip IDT_ENTRIES * 16
>
>
You are aligning the IDT *descriptor*, not the IDT itself?
-hpa
next prev parent reply other threads:[~2013-07-12 22:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-12 18:30 [PATCH] x86: make sure IDT is page aligned Kees Cook
2013-07-12 22:27 ` H. Peter Anvin [this message]
2013-07-12 22:28 ` H. Peter Anvin
2013-07-12 22:43 ` Kees Cook
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