linux-kernel - Re: [PATCH v2 0/5] Introduce new wrappers to copy user-arrays

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Message-ID: <ACD75DAA-AF42-486C-B44B-9272EF302E3D@kernel.org>
Date:   Mon, 11 Sep 2023 19:32:34 -0700
From:   Kees Cook <kees@...nel.org>
To:     Dave Airlie <airlied@...il.com>
CC:     Philipp Stanner <pstanner@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Andy Shevchenko <andy@...nel.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Christian Brauner <brauner@...nel.org>,
        David Disseldorp <ddiss@...e.de>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Siddh Raman Pant <code@...dh.me>,
        Nick Alcock <nick.alcock@...cle.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel@...ll.ch>, Zack Rusin <zackr@...are.com>,
        VMware Graphics Reviewers 
        <linux-graphics-maintainer@...are.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 0/5] Introduce new wrappers to copy user-arrays

On September 11, 2023 6:55:32 PM PDT, Dave Airlie <airlied@...il.com> wrote:
>On Tue, 12 Sept 2023 at 11:27, Kees Cook <kees@...nel.org> wrote:
>>
>> On September 8, 2023 12:59:39 PM PDT, Philipp Stanner <pstanner@...hat.com> wrote:
>> >Hi!
>> >
>> >David Airlie suggested that we could implement new wrappers around
>> >(v)memdup_user() for duplicating user arrays.
>> >
>> >This small patch series first implements the two new wrapper functions
>> >memdup_array_user() and vmemdup_array_user(). They calculate the
>> >array-sizes safely, i.e., they return an error in case of an overflow.
>> >
>> >It then implements the new wrappers in two components in kernel/ and two
>> >in the drm-subsystem.
>> >
>> >In total, there are 18 files in the kernel that use (v)memdup_user() to
>> >duplicate arrays. My plan is to provide patches for the other 14
>> >successively once this series has been merged.
>> >
>> >
>> >Changes since v1:
>> >- Insert new headers alphabetically ordered
>> >- Remove empty lines in functions' docstrings
>> >- Return -EOVERFLOW instead of -EINVAL from wrapper functions
>> >
>> >
>> >@Andy:
>> >I test-build it for UM on my x86_64. Builds successfully.
>> >A kernel build (localmodconfig) for my Fedora38 @ x86_64 does also boot
>> >fine.
>> >
>> >If there is more I can do to verify the early boot stages are fine,
>> >please let me know!
>> >
>> >P.
>> >
>> >Philipp Stanner (5):
>> >  string.h: add array-wrappers for (v)memdup_user()
>> >  kernel: kexec: copy user-array safely
>> >  kernel: watch_queue: copy user-array safely
>> >  drm_lease.c: copy user-array safely
>> >  drm: vmgfx_surface.c: copy user-array safely
>> >
>> > drivers/gpu/drm/drm_lease.c             |  4 +--
>> > drivers/gpu/drm/vmwgfx/vmwgfx_surface.c |  4 +--
>> > include/linux/string.h                  | 40 +++++++++++++++++++++++++
>> > kernel/kexec.c                          |  2 +-
>> > kernel/watch_queue.c                    |  2 +-
>> > 5 files changed, 46 insertions(+), 6 deletions(-)
>> >
>>
>> Nice. For the series:
>>
>> Reviewed-by: Kees Cook <keescook@...omium.org>
>
>Hey Kees,
>
>what tree do you think it would best to land this through? I'm happy
>to send the initial set from a drm branch, but also happy to have it
>land via someone with a better process.

Feel free to take it via drm. Usually string.h doesn't get a lot of changes (and even then it's normally additive) so conflicts are rare/easy. :)

-Kees


-- 
Kees Cook