linux-kernel - Re: [PATCH] drm/plane: Move range check for format

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Message-ID: <YmqsGhEzaZsdZs3u@e110455-lin.cambridge.arm.com>
Date:   Thu, 28 Apr 2022 16:00:42 +0100
From:   Liviu Dudau <liviu.dudau@....com>
To:     Steven Price <steven.price@....com>
Cc:     David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH] drm/plane: Move range check for format_count earlier

On Thu, Apr 28, 2022 at 12:57:52PM +0100, Steven Price wrote:
> On 03/12/2021 13:08, Liviu Dudau wrote:
> > On Fri, Dec 03, 2021 at 10:28:15AM +0000, Steven Price wrote:
> >> While the check for format_count > 64 in __drm_universal_plane_init()
> >> shouldn't be hit (it's a WARN_ON), in its current position it will then
> >> leak the plane->format_types array and fail to call
> >> drm_mode_object_unregister() leaking the modeset identifier. Move it to
> >> the start of the function to avoid allocating those resources in the
> >> first place.
> >>
> >> Signed-off-by: Steven Price <steven.price@....com>
> > 
> > Well spotted!
> > 
> > Reviewed-by: Liviu Dudau <liviu.dudau@....com>
> > 
> > I'm going to wait to see if anyone else has any comments before I'll merge this into
> > drm-misc-fixes (or should it be drm-misc-next-fixes?)
> 
> Gentle ping! I think we've probably waited long enough. Are you going to
> merge this or would you like me to?

Apologies for dropping this! I will push this one today.

Best regards,
Liviu

> 
> Thanks,
> 
> Steve
> 
> > Best regards,
> > Liviu
> > 
> >> ---
> >>  drivers/gpu/drm/drm_plane.c | 14 +++++++-------
> >>  1 file changed, 7 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> >> index 82afb854141b..fd0bf90fb4c2 100644
> >> --- a/drivers/gpu/drm/drm_plane.c
> >> +++ b/drivers/gpu/drm/drm_plane.c
> >> @@ -249,6 +249,13 @@ static int __drm_universal_plane_init(struct drm_device *dev,
> >>  	if (WARN_ON(config->num_total_plane >= 32))
> >>  		return -EINVAL;
> >>  
> >> +	/*
> >> +	 * First driver to need more than 64 formats needs to fix this. Each
> >> +	 * format is encoded as a bit and the current code only supports a u64.
> >> +	 */
> >> +	if (WARN_ON(format_count > 64))
> >> +		return -EINVAL;
> >> +
> >>  	WARN_ON(drm_drv_uses_atomic_modeset(dev) &&
> >>  		(!funcs->atomic_destroy_state ||
> >>  		 !funcs->atomic_duplicate_state));
> >> @@ -270,13 +277,6 @@ static int __drm_universal_plane_init(struct drm_device *dev,
> >>  		return -ENOMEM;
> >>  	}
> >>  
> >> -	/*
> >> -	 * First driver to need more than 64 formats needs to fix this. Each
> >> -	 * format is encoded as a bit and the current code only supports a u64.
> >> -	 */
> >> -	if (WARN_ON(format_count > 64))
> >> -		return -EINVAL;
> >> -
> >>  	if (format_modifiers) {
> >>  		const uint64_t *temp_modifiers = format_modifiers;
> >>  
> >> -- 
> >> 2.25.1
> >>
> > 
> 

-- 
====================
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| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
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