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Date: Wed, 24 Jan 2018 15:40:40 +0100
From: Jiri Slaby <jslaby@...e.cz>
To: Dan Williams <dan.j.williams@...el.com>, linux-kernel@...r.kernel.org
Cc: linux-arch@...r.kernel.org, kernel-hardening@...ts.openwall.com,
gregkh@...uxfoundation.org, x86@...nel.org, Ingo Molnar <mingo@...hat.com>,
Andy Lutomirski <luto@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
tglx@...utronix.de, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...ux.intel.com
Subject: Re: [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read
under speculation
On 01/19/2018, 01:02 AM, Dan Williams wrote:
> The syscall table base is a user controlled function pointer in kernel
> space. Like, 'get_user, use 'MASK_NOSPEC' to prevent any out of bounds
> speculation. While retpoline prevents speculating into the user
> controlled target it does not stop the pointer de-reference, the concern
> is leaking memory relative to the syscall table base.
>
> Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: x86@...nel.org
> Cc: Andy Lutomirski <luto@...nel.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> arch/x86/entry/entry_64.S | 2 ++
> arch/x86/include/asm/smap.h | 9 ++++++++-
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
> index 4f8e1d35a97c..2320017077d4 100644
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -35,6 +35,7 @@
> #include <asm/asm.h>
> #include <asm/smap.h>
> #include <asm/pgtable_types.h>
> +#include <asm/smap.h>
This is already included 2 lines above
thanks,
--
js
suse labs
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