linux-kernel - Re: [PATCH 00/15] v5 kernel core pieces refcount conversions

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Date:   Thu, 31 Aug 2017 16:48:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Elena Reshetova <elena.reshetova@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Al Viro <viro@...iv.linux.org.uk>, Tejun Heo <tj@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Li Zefan <lizefan@...wei.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Eric Paris <eparis@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, dvhart@...radead.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH 00/15] v5 kernel core pieces refcount conversions

On Wed, Aug 30, 2017 at 5:22 AM, Elena Reshetova
<elena.reshetova@...el.com> wrote:
> Now we have at least x86 support for ARCH_HAS_REFCOUNT merged and
> arm and others on their way.
>
> Changes in v5:
>  * Kees catched that the following changes in
>    perf_event_context.refcount and futex_pi_state.refcount
>    are not correct now when ARCH_HAS_REFCOUNT is enabled:
>     -   WARN_ON(!atomic_inc_not_zero(refcount));
>     +   refcount_inc(refcount);
>    So they are now changed back to using refcount_inc_not_zero.

Thanks!

Reviewed-by: Kees Cook <keescook@...omium.org>

Andrew, are you able to carry these patches in -mm, since they span a
bunch of core kernel areas?

-Kees

>
> Changes in v4:
>  * just rebase and corrections on linux-next/master
>
> Changes in v3:
>  * SoB chain corrected
>  * minor corrections based on v2 feedback
>  * rebase on linux-next/master as of today
>
> Changes in v2:
>  * dropped already merged patches
>  * rebase on top of linux-next/master
>  * Now by default refcount_t = atomic_t (*) and uses all atomic
>    standard operations unless CONFIG_REFCOUNT_FULL is enabled.
>    This is a compromise for the systems that are critical on
>    performance (such as net) and cannot accept even slight delay
>    on the refcounter operations.
>
> This series, for core kernel components, replaces atomic_t reference
> counters with the new refcount_t type and API (see include/linux/refcount.h).
> By doing this we prevent intentional or accidental
> underflows or overflows that can led to use-after-free vulnerabilities.
>
> The patches are fully independent and can be cherry-picked separately.
> If there are no objections to the patches, please merge them via respective trees.
>
>
> Elena Reshetova (15):
>   sched: convert sighand_struct.count to refcount_t
>   sched: convert signal_struct.sigcnt to refcount_t
>   sched: convert user_struct.__count to refcount_t
>   sched: convert numa_group.refcount to refcount_t
>   sched/task_struct: convert task_struct.usage to refcount_t
>   sched/task_struct: convert task_struct.stack_refcount to refcount_t
>   perf: convert perf_event_context.refcount to refcount_t
>   perf/ring_buffer: convert ring_buffer.refcount to refcount_t
>   perf/ring_buffer: convert ring_buffer.aux_refcount to refcount_t
>   uprobes: convert uprobe.ref to refcount_t
>   nsproxy: convert nsproxy.count to refcount_t
>   groups: convert group_info.usage to refcount_t
>   creds: convert cred.usage to refcount_t
>   futex: convert futex_pi_state.refcount to refcount_t
>   kcov: convert kcov.refcount to refcount_t
>
>  fs/exec.c                        |  4 ++--
>  fs/proc/task_nommu.c             |  2 +-
>  include/linux/cred.h             | 13 ++++++------
>  include/linux/init_task.h        |  7 +++---
>  include/linux/nsproxy.h          |  6 +++---
>  include/linux/perf_event.h       |  3 ++-
>  include/linux/sched.h            |  5 +++--
>  include/linux/sched/signal.h     |  5 +++--
>  include/linux/sched/task.h       |  4 ++--
>  include/linux/sched/task_stack.h |  2 +-
>  include/linux/sched/user.h       |  5 +++--
>  kernel/cred.c                    | 46 ++++++++++++++++++++--------------------
>  kernel/events/core.c             | 18 ++++++++--------
>  kernel/events/internal.h         |  5 +++--
>  kernel/events/ring_buffer.c      |  8 +++----
>  kernel/events/uprobes.c          |  8 +++----
>  kernel/fork.c                    | 24 ++++++++++-----------
>  kernel/futex.c                   | 13 ++++++------
>  kernel/groups.c                  |  2 +-
>  kernel/kcov.c                    |  9 ++++----
>  kernel/nsproxy.c                 |  6 +++---
>  kernel/sched/fair.c              | 12 +++++------
>  kernel/user.c                    |  8 +++----
>  23 files changed, 112 insertions(+), 103 deletions(-)
>
> --
> 2.7.4
>



-- 
Kees Cook
Pixel Security