Re: [PATCH 073/190] Revert "media: rcar_drif: fix a memory disclosure"

Mauro Carvalho Chehab
2021-04-22T09:03:47Z

Em Thu, 22 Apr 2021 09:29:36 +0200
Hans Verkuil <hverkuil-cisco@xs4all.nl> escreveu:

> On 22/04/2021 08:57, Geert Uytterhoeven wrote:
> > Hi Laurent,
> >
> > On Wed, Apr 21, 2021 at 11:22 PM Laurent Pinchart
> > <laurent.pinchart@ideasonboard.com> wrote:
> >> On Wed, Apr 21, 2021 at 08:58:22PM +0200, Geert Uytterhoeven wrote:
> >>> On Wed, Apr 21, 2021 at 3:06 PM Greg Kroah-Hartman wrote:
> >>>> This reverts commit d39083234c60519724c6ed59509a2129fd2aed41.
> >>>>
> >>>> Commits from @umn.edu addresses have been found to be submitted in "bad
> >>>> faith" to try to test the kernel community's ability to review "known
> >>>> malicious" changes. The result of these submissions can be found in a
> >>>> paper published at the 42nd IEEE Symposium on Security and Privacy
> >>>> entitled, "Open Source Insecurity: Stealthily Introducing
> >>>> Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
> >>>> of Minnesota) and Kangjie Lu (University of Minnesota).
> >>>>
> >>>> Because of this, all submissions from this group must be reverted from
> >>>> the kernel tree and will need to be re-reviewed again to determine if
> >>>> they actually are a valid fix. Until that work is complete, remove this
> >>>> change to ensure that no problems are being introduced into the
> >>>> codebase.
> >>>>
> >>>> Cc: Kangjie Lu <kjlu@umn.edu>
> >>>> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> >>>> Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> >>>> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> >>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>>
> >>> Upon a second look, I still see nothing wrong with the original commit.
> >>> However, as I'm no v4l expert, I'd like to defer to the experts for final
> >>> judgement.
> >>
> >> It seems fine to me, but it also seems unneeded, as the V4L2 core clears
> >> the whole f->fmt union before calling this operation. The revert will
> >> this improve performance very slightly.
> >
> > Hmm, that means very recent commit f12b81e47f48940a ("media: core
> > headers: fix kernel-doc warnings") is not fully correct, as it added
> > kerneldoc stating this is the responsibility of the driver:
> >
> > + * @reserved: drivers and applications must zero this array
>
> Actually, it is the V4L2 core used by the driver that zeroes this. So
> drivers don't need to do this, it's done for them. It used to be the
> responsibility of the driver itself, but this was all moved to the core
> framework a long time ago since, duh!, drivers always forgot this :-)
>
> >
> > Anyway, it doesn't look like this umn.edu patch introduced a bug.
>
> I haven't seen any bugs introduced by the media patches from umn.edu.

Hi Greg,

I also double-checked all media revert patches from:

git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git umn.edu-reverts

currently on this patch:
6f4747a872ad Revert "ethtool: fix a potential missing-check bug"

That's a summary of what I found:

All of those should be dropped from your tree:

84fdb5856edd Revert "media: si2165: fix a missing check of return value"
867043f2206e Revert "media: video-mux: fix null pointer dereferences"
78ae4b621297 Revert "media: cx231xx: replace BUG_ON with recovery code"
5be328a55817 Revert "media: saa7146: Avoid using BUG_ON as an assertion"
81ce83158d22 Revert "media: davinci/vpfe_capture.c: Avoid BUG_ON for register failure"
3319b39504b8 Revert "media: media/saa7146: fix incorrect assertion in saa7146_buffer_finish"
b393f7cb29a2 Revert "media: rcar-vin: Fix a reference count leak."
197bc5d03682 Revert "media: rcar-vin: Fix a reference count leak."
2fd9cf68bbb6 Revert "media: rockchip/rga: Fix a reference count leak."
d1e4614eca24 Revert "media: platform: fcp: Fix a reference count leak."
416e8a6ae07f Revert "media: camss: Fix a reference count leak."
06b793ae497b Revert "media: s5p-mfc: Fix a reference count leak"
8f9fc14a7cc9 Revert "media: stm32-dcmi: Fix a reference count leak"
556e1f86ba24 Revert "media: ti-vpe: Fix a missing check and reference count leak"
5f5b1722ad0d Revert "media: exynos4-is: Fix a reference count leak"
f4c758c6c1cb Revert "media: exynos4-is: Fix a reference count leak due to pm_runtime_get_sync"
beb717878c73 Revert "media: exynos4-is: Fix several reference count leaks due to pm_runtime_get_sync
7066ec748bfd Revert "media: sti: Fix reference count leaks"
cdd117093b19 Revert "media: st-delta: Fix reference count leak in delta_run_work"

As, after my re-check, they all seem to be addressing real issues. So,
NACK on those.

This patch (073/190):

899ab4671bc0 Revert "media: rcar_drif: fix a memory disclosure"

While it doesn't hurt, it is useless, as the media core already
prevents memory disclosure. So, it should be reverted.

So, for patch 073/190:

Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Thanks,
Mauro