From: Thomas Garnier <thgarnie@google.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Martin Schwidefsky" <schwidefsky@de.ibm.com>,
"Heiko Carstens" <heiko.carstens@de.ibm.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"David Howells" <dhowells@redhat.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Arnd Bergmann" <arnd@arndb.de>,
"René Nyffenegger" <mail@renenyffenegger.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
"Ingo Molnar" <mingo@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Oleg Nesterov" <oleg@redhat.com>,
"Pavel Tikhomirov" <ptikhomirov@virtuozzo.com>,
"Stephen Smalley" <sds@tycho.nsa.gov>,
"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>,
"Kees Cook" <keescook@chromium.org>,
"Josh Poimboeuf" <jpoimboe@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Brian Gerst" <brgerst@gmail.com>
Subject: Re: [PATCH v4 1/4] syscalls: Restore address limit after a syscall
Date: Wed, 22 Mar 2017 13:49:51 -0700 [thread overview]
Message-ID: <CAJcbSZGLAXmE_mFZMAZgioWExzm3A4vXBKLGJ7DZNAbJOcH8Zw@mail.gmail.com> (raw)
In-Reply-To: <CALCETrV6K8iSfAwojMFyLrbb3CG2aF4k5hPWc7EDV4ErPDq64w@mail.gmail.com>
On Wed, Mar 22, 2017 at 1:44 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> On Wed, Mar 22, 2017 at 1:38 PM, Thomas Garnier <thgarnie@google.com> wrote:
>> This patch ensures a syscall does not return to user-mode with a kernel
>> address limit. If that happened, a process can corrupt kernel-mode
>> memory and elevate privileges.
>>
>> For example, it would mitigation this bug:
>>
>> - https://bugs.chromium.org/p/project-zero/issues/detail?id=990
>>
>> If the CONFIG_BUG_ON_DATA_CORRUPTION option is enabled, an incorrect
>> state will result in a BUG_ON.
>
> I'm a bit confused about this choice of configurability. I can see
> two sensible choices:
>
> 1. Enable this hardening feature: BUG if there's an exploitable bug.
>
> 2. Don't enable it at all.
>
> While it's possible that silently papering over the bug is slightly
> faster than BUGging, it will allow bugs to continue to exist
> undetected.
We can default to BUGging. I think my approach was avoiding doing a
BUG_ON just to avoid breaking people.
>
> --Andy
--
Thomas
next prev parent reply other threads:[~2017-03-22 20:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-22 20:38 [PATCH v4 1/4] syscalls: Restore address limit after a syscall Thomas Garnier
2017-03-22 20:38 ` [PATCH v4 2/4] x86/syscalls: Specific usage of verify_pre_usermode_state Thomas Garnier
2017-03-22 20:38 ` [PATCH v4 3/4] arm/syscalls: " Thomas Garnier
[not found] ` <20170322203834.67556-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-03-22 20:38 ` [PATCH v4 4/4] arm64/syscalls: " Thomas Garnier
2017-03-22 20:44 ` [PATCH v4 1/4] syscalls: Restore address limit after a syscall Andy Lutomirski
2017-03-22 20:49 ` Thomas Garnier [this message]
2017-03-22 20:54 ` H. Peter Anvin
2017-03-23 15:14 ` Thomas Garnier
2017-03-23 15:32 ` Borislav Petkov
[not found] ` <20170323153204.4lxglq6jlvvxp6ev-fF5Pk5pvG8Y@public.gmane.org>
2017-03-23 15:40 ` Thomas Garnier
2017-03-22 20:54 ` H. Peter Anvin
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