On Wed, Aug 26, 2026 at 04:56:03PM +0200, Boris Brezillon wrote:
> If we don't do that, we might face various UAFs, because the resource
> referenced by these work items might be gone by the time they get
> executed.
>
> In each subcomponent making use of the panthor_cleanup_wq, we add a
> flush_workqueue() at the end of the _unplug() function. Note that this
> assumes no more work items from this subcomponent gets queued after
> that point, which is not yet guaranteed, but this will be fixed in
> upcoming changes.
>
> Fixes: de8548813824 ("drm/panthor: Add the scheduler logical block")
> Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
> Reported-by: [email protected]
> Closes:
> https://sashiko.dev/#/patchset/[email protected]?part=2
> Signed-off-by: Boris Brezillon <[email protected]>
Reviewed-by: Liviu Dudau <[email protected]>
Best regards,
Liviu
> ---
> drivers/gpu/drm/panthor/panthor_mmu.c | 6 ++++++
> drivers/gpu/drm/panthor/panthor_sched.c | 6 ++++++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c
> b/drivers/gpu/drm/panthor/panthor_mmu.c
> index d43ba1c7cd2a..1385ee28bee5 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -3367,6 +3367,12 @@ void panthor_mmu_unplug(struct panthor_device *ptdev)
> }
> }
> mutex_unlock(&ptdev->mmu->as.slots_lock);
> +
> + /* Ensure any pending job cleanup work are executed before returning,
> + * otherwise those might access objects that are gone if the work is
> + * executed after other components are unplugged.
> + */
> + flush_workqueue(panthor_cleanup_wq);
> }
>
> static void panthor_mmu_release_wq(struct drm_device *ddev, void *res)
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c
> b/drivers/gpu/drm/panthor/panthor_sched.c
> index 42adfc76b9e1..a6d57dc1b43e 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -4049,6 +4049,12 @@ void panthor_sched_unplug(struct panthor_device *ptdev)
> sched->pm.has_ref = false;
> }
> mutex_unlock(&sched->lock);
> +
> + /* Ensure any pending group release work are executed before returning,
> + * otherwise those might access objects that are gone if the work is
> + * executed after other components are unplugged.
> + */
> + flush_workqueue(panthor_cleanup_wq);
> }
>
> static void panthor_sched_fini(struct drm_device *ddev, void *res)
>
> --
> 2.55.0
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
