From: Kristen Carlson Accardi <kristen@linux.intel.com>
To: Kees Cook <keescook@chromium.org>
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
Jonathan Corbet <corbet@lwn.net>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
arjan@linux.intel.com, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com,
Tony Luck <tony.luck@intel.com>,
linux-doc@vger.kernel.org
Subject: Re: [PATCH v2 7/9] x86: Add support for function granular KASLR
Date: Thu, 21 May 2020 14:42:56 -0700 [thread overview]
Message-ID: <7c8685090dd36ab0175ae91d1421f4cd7fb6aff0.camel@linux.intel.com> (raw)
In-Reply-To: <202005211301.4853672E2@keescook>
Hi Kees,
Thanks for your review - I will incorporate what I can into v3, or
explain why not once I give it a try :).
On Thu, 2020-05-21 at 14:08 -0700, Kees Cook wrote:
> >
<snip>
> On Thu, May 21, 2020 at 09:56:38AM -0700, Kristen Carlson Accardi
> wrote:
> > + /*
> > + * sometimes we are updating a relative offset that would
> > + * normally be relative to the next instruction (such as a
> > call).
> > + * In this case to calculate the target, you need to add 32bits
> > to
> > + * the pc to get the next instruction value. However, sometimes
> > + * targets are just data that was stored in a table such as
> > ksymtab
> > + * or cpu alternatives. In this case our target is not relative
> > to
> > + * the next instruction.
> > + */
>
> Excellent and scary comment. ;) Was this found by trial and error?
> That
> sounds "fun" to debug. :P
This did suck to debug. Thank goodness for debugging with gdb in a VM.
As you know, I had previously had a patch to use a prand to be able to
retain the same layout across boots, and that came in handy here. While
we decided to not submit this functionality with this initial merge
attempt, I will add it on in the future as it does make debugging much
easier when you can reliably duplicate failure modes.
next prev parent reply other threads:[~2020-05-21 21:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 16:56 [PATCH v2 0/9] Function Granular KASLR Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 1/9] objtool: Do not assume order of parent/child functions Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 2/9] x86: tools/relocs: Support >64K section headers Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 3/9] x86/boot: Allow a "silent" kaslr random byte fetch Kristen Carlson Accardi
2020-05-21 16:56 ` [PATCH v2 4/9] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Kristen Carlson Accardi
2020-05-21 20:00 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 5/9] x86: Make sure _etext includes function sections Kristen Carlson Accardi
2020-05-21 18:11 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 6/9] x86/tools: Add relative relocs for randomized functions Kristen Carlson Accardi
2020-05-21 19:54 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 7/9] x86: Add support for function granular KASLR Kristen Carlson Accardi
2020-05-21 21:08 ` Kees Cook
2020-05-21 21:42 ` Kristen Carlson Accardi [this message]
2020-06-04 17:27 ` Kristen Carlson Accardi
2020-06-04 22:37 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 8/9] kallsyms: Hide layout Kristen Carlson Accardi
2020-05-21 21:14 ` Kees Cook
2020-05-21 16:56 ` [PATCH v2 9/9] module: Reorder functions Kristen Carlson Accardi
2020-05-21 21:33 ` Kees Cook
2020-06-09 20:14 ` Kristen Carlson Accardi
2020-06-09 20:42 ` Kees Cook
2020-06-09 20:59 ` Kristen Carlson Accardi
2020-05-21 21:54 ` [PATCH v2 0/9] Function Granular KASLR Kees Cook
2020-05-21 22:26 ` Thomas Gleixner
2020-05-21 23:30 ` Kees Cook
2020-05-21 23:43 ` Thomas Gleixner
2020-05-21 23:44 ` Kristen Carlson Accardi
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