2022-06-18 01:04:41

by Brian Norris

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Subject: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

It's possible for users to try to duplicate the CRTC state even when the
state doesn't exist. drm_atomic_helper_crtc_duplicate_state() (and other
users of __drm_atomic_helper_crtc_duplicate_state()) already guard this
with a WARN_ON() instead of crashing, so let's do that here too.

Signed-off-by: Brian Norris <[email protected]>
---

drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index 74562d40f639..daf192881353 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1570,6 +1570,9 @@ static struct drm_crtc_state *vop_crtc_duplicate_state(struct drm_crtc *crtc)
{
struct rockchip_crtc_state *rockchip_state;

+ if (WARN_ON(!crtc->state))
+ return NULL;
+
rockchip_state = kzalloc(sizeof(*rockchip_state), GFP_KERNEL);
if (!rockchip_state)
return NULL;
--
2.36.1.476.g0c4daa206d-goog


2022-06-23 16:54:22

by Sean Paul

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

On Fri, Jun 17, 2022 at 05:26:52PM -0700, Brian Norris wrote:
> It's possible for users to try to duplicate the CRTC state even when the
> state doesn't exist. drm_atomic_helper_crtc_duplicate_state() (and other
> users of __drm_atomic_helper_crtc_duplicate_state()) already guard this
> with a WARN_ON() instead of crashing, so let's do that here too.
>
> Signed-off-by: Brian Norris <[email protected]>

Thanks for this patch!

Reviewed-by: Sean Paul <[email protected]>

> ---
>
> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index 74562d40f639..daf192881353 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -1570,6 +1570,9 @@ static struct drm_crtc_state *vop_crtc_duplicate_state(struct drm_crtc *crtc)
> {
> struct rockchip_crtc_state *rockchip_state;
>
> + if (WARN_ON(!crtc->state))
> + return NULL;
> +
> rockchip_state = kzalloc(sizeof(*rockchip_state), GFP_KERNEL);
> if (!rockchip_state)
> return NULL;
> --
> 2.36.1.476.g0c4daa206d-goog
>

--
Sean Paul, Software Engineer, Google / Chromium OS

2022-06-23 23:48:28

by Doug Anderson

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

Hi,

On Fri, Jun 17, 2022 at 5:27 PM Brian Norris <[email protected]> wrote:
>
> It's possible for users to try to duplicate the CRTC state even when the
> state doesn't exist. drm_atomic_helper_crtc_duplicate_state() (and other
> users of __drm_atomic_helper_crtc_duplicate_state()) already guard this
> with a WARN_ON() instead of crashing, so let's do that here too.
>
> Signed-off-by: Brian Norris <[email protected]>
> ---
>
> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 +++
> 1 file changed, 3 insertions(+)

I'm not an expert in this area, but it makes sense to me to match
drm_atomic_helper_crtc_duplicate_state() in this way. Thus:

Reviewed-by: Douglas Anderson <[email protected]>

I would tend to assume that this would be landed in drm-misc by Heiko
if he's good with it. After several weeks of silence, however, I'll
commit it myself.

-Doug

2022-06-24 07:31:02

by Heiko Stübner

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

Am Freitag, 24. Juni 2022, 01:44:52 CEST schrieb Doug Anderson:
> Hi,
>
> On Fri, Jun 17, 2022 at 5:27 PM Brian Norris <[email protected]> wrote:
> >
> > It's possible for users to try to duplicate the CRTC state even when the
> > state doesn't exist. drm_atomic_helper_crtc_duplicate_state() (and other
> > users of __drm_atomic_helper_crtc_duplicate_state()) already guard this
> > with a WARN_ON() instead of crashing, so let's do that here too.
> >
> > Signed-off-by: Brian Norris <[email protected]>
> > ---
> >
> > drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 +++
> > 1 file changed, 3 insertions(+)
>
> I'm not an expert in this area, but it makes sense to me to match
> drm_atomic_helper_crtc_duplicate_state() in this way. Thus:
>
> Reviewed-by: Douglas Anderson <[email protected]>
>
> I would tend to assume that this would be landed in drm-misc by Heiko
> if he's good with it. After several weeks of silence, however, I'll
> commit it myself.

I do tend to batch up drm-misc patches, as that is always a different
workflow but I'll pick that up :-)

The interesting question would be, do we want some fixes tag for it?


Heiko


2022-06-24 18:05:35

by Brian Norris

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

On Fri, Jun 24, 2022 at 12:23 AM Heiko Stuebner <[email protected]> wrote:
> The interesting question would be, do we want some fixes tag for it?

I'm not aware of any currently-upstream code that will hit this [1].
I've hit it in out-of-tree code (or, code that I submitted to
dri-devel, but wasn't accepted as-is), and this is the "belt and
braces" part -- the primary fix is that we should avoid calling things
like drm_atomic_get_crtc_state() at inappropriate times.

So, is the "extra safety" check really something that should go to
-stable? (Because let's be honest, everything with a Fixes tag goes
there.) Maybe?

Anyway, if you want to "blame" anything, this commit actually dropped
the safety check:

4e257d9eee23 drm/rockchip: get rid of rockchip_drm_crtc_mode_config

Brian

[1] But I'm not omniscient. So maybe it's good to have anyway.

2022-06-24 20:57:59

by Heiko Stübner

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

Am Freitag, 24. Juni 2022, 19:57:53 CEST schrieb Brian Norris:
> On Fri, Jun 24, 2022 at 12:23 AM Heiko Stuebner <[email protected]> wrote:
> > The interesting question would be, do we want some fixes tag for it?
>
> I'm not aware of any currently-upstream code that will hit this [1].
> I've hit it in out-of-tree code (or, code that I submitted to
> dri-devel, but wasn't accepted as-is), and this is the "belt and
> braces" part -- the primary fix is that we should avoid calling things
> like drm_atomic_get_crtc_state() at inappropriate times.
>
> So, is the "extra safety" check really something that should go to
> -stable? (Because let's be honest, everything with a Fixes tag goes
> there.) Maybe?
>
> Anyway, if you want to "blame" anything, this commit actually dropped
> the safety check:
>
> 4e257d9eee23 drm/rockchip: get rid of rockchip_drm_crtc_mode_config

I tend to think, if we know that connection we should also include it :-) .
I wouldn't include a cc-stable for the reason you mentioned, but to me
it makes sense if someone reading the git history in the future can easily
know that information - so it doesn't hurt :-) .

So I'll add that when applying.

Thanks for supplying the origin commit
Heiko

>
> Brian
>
> [1] But I'm not omniscient. So maybe it's good to have anyway.
>




2022-07-03 11:46:17

by Heiko Stübner

[permalink] [raw]
Subject: Re: [PATCH] drm/rockchip: vop: Don't crash for invalid duplicate_state()

On Fri, 17 Jun 2022 17:26:52 -0700, Brian Norris wrote:
> It's possible for users to try to duplicate the CRTC state even when the
> state doesn't exist. drm_atomic_helper_crtc_duplicate_state() (and other
> users of __drm_atomic_helper_crtc_duplicate_state()) already guard this
> with a WARN_ON() instead of crashing, so let's do that here too.

Applied, thanks!

[1/1] drm/rockchip: vop: Don't crash for invalid duplicate_state()
commit: 1449110b0dade8b638d2c17ab7c5b0ff696bfccb

Best regards,
--
Heiko Stuebner <[email protected]>