[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <1466817192-9586-1-git-send-email-jannh@google.com>
Date: Sat, 25 Jun 2016 03:13:11 +0200
From: Jann Horn <jannh@...gle.com>
To: linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Cc: pageexec@...email.hu,
Kees Cook <keescook@...gle.com>,
jann@...jh.net,
Jann Horn <jannh@...gle.com>
Subject: [RFC] reference count hardening via kref: another attempt
I would like to harden the kernel against reference count
overflow bugs. The commit message of the patch contains
a short analysis of code size impact, an explanation why I
want reference count hardening to land in the kernel, and a
description of the algorithm I'd want to use.
The reason I'm writing a cover letter is that my patch, on
its own, is pretty useless: My patch only adds hardening to
struct kref, but nearly all reference counters are
currently implemented using atomic_t, which is a generic
atomic number type. For the patch to be useful, I'll have
to go through the kernel and, for every atomic_t, decide
whether it is a reference count and, if so, change it
(together with all accesses to it) to a kref. According to
a quick grep, there are currently about 2700 atomic_t
struct members or variables in the kernel, so it's going to
be a big amount of work, and the resulting patches will be
gigantic.
Therefore, before I actually spend lots of time on this,
I'd like to know:
- Does the reference count hardening in my patch look
okay, and does it have good chances to get accepted
when submitted for inclusion in the kernel at a later
point in time?
- If I manually go through the kernel and write a
gigantic atomic_t -> struct kref patch (or a few
patches coarsely grouped by subsystem), how high is
the probability that it will get accepted?
(Note: I won't have much time for kernel work in the next
four months or so - but afterwards, I could probably
allocate time for getting this done.)
Jann Horn (1):
kref: pin objects with dangerously high reference count
include/linux/kref.h | 39 +++++++++++++++++++++++++++++++++------
init/Kconfig | 16 ++++++++++++++++
kernel/Makefile | 2 +-
kernel/kref.c | 17 +++++++++++++++++
4 files changed, 67 insertions(+), 7 deletions(-)
create mode 100644 kernel/kref.c
--
2.8.0.rc3.226.g39d4020
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
