From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Garnier <thgarnie@google.com>
Subject: Re: [PATCH v10 3/3] arm64/syscalls: Check address limit on user-mode return
Date: Wed, 21 Jun 2017 06:57:44 -0700
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References: <20170615011203.144108-1-thgarnie@google.com> <20170615011203.144108-3-thgarnie@google.com>
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To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>, Rik van Riel <riel@redhat.com>, Oleg Nesterov <oleg@redhat.com>, Josh Poimboeuf <jpoimboe@redhat.com>, Petr Mladek <pmladek@suse.com>, Miroslav Benes <mbenes@suse.cz>, Kees Cook <keescook@chromium.org>, Al Viro <viro@zeniv.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>, Dave Hansen <dave.hansen@intel.com>, David Howells <dhowells@redhat.com>, Russell King <linux@armlinux.org.uk>, Andy Lutomirski <luto@amacapital.net>, Will Drewry <wad@chromium.org>, Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>, Pratyush Anand <panand@redhat.com>
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On Wed, Jun 21, 2017 at 1:16 AM, Catalin Marinas
<catalin.marinas@arm.com> wrote:
> On Wed, Jun 14, 2017 at 06:12:03PM -0700, Thomas Garnier wrote:
>> Ensure the address limit is a user-mode segment before returning to
>> user-mode. Otherwise a process can corrupt kernel-mode memory and
>> elevate privileges [1].
>>
>> The set_fs function sets the TIF_SETFS flag to force a slow path on
>> return. In the slow path, the address limit is checked to be USER_DS if
>> needed.
>>
>> [1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990
>>
>> Signed-off-by: Thomas Garnier <thgarnie@google.com>
>> ---
>> v10 redesigns the change to use work flags on set_fs as recommended by
>> Linus and agreed by others.
>>
>> Based on next-20170609
>> ---
>>  arch/arm64/include/asm/thread_info.h | 4 +++-
>>  arch/arm64/include/asm/uaccess.h     | 3 +++
>>  arch/arm64/kernel/signal.c           | 5 +++++
>>  3 files changed, 11 insertions(+), 1 deletion(-)
>
> For arm64:
>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Thanks Catalin

-- 
Thomas