Re: [PATCH v9 5/5] drm/panthor: Fix race condition when gathering fdinfo group samples

Steven Price
2025-01-24T16:18:51Z

On 23/01/2025 22:53, Adrián Larumbe wrote:
> Commit e16635d88fa0 ("drm/panthor: add DRM fdinfo support") failed to
> protect access to groups with an xarray lock, which could lead to
> use-after-free errors.
>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
> Fixes: e16635d88fa0 ("drm/panthor: add DRM fdinfo support")

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
> drivers/gpu/drm/panthor/panthor_sched.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index e6c08a694e41..1d283b4bab86 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -2865,6 +2865,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
> if (IS_ERR_OR_NULL(gpool))
> return;
>
> + xa_lock(&gpool->xa);
> xa_for_each(&gpool->xa, i, group) {
> mutex_lock(&group->fdinfo.lock);
> pfile->stats.cycles += group->fdinfo.data.cycles;
> @@ -2873,6 +2874,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
> group->fdinfo.data.time = 0;
> mutex_unlock(&group->fdinfo.lock);
> }
> + xa_unlock(&gpool->xa);
> }
>
> static void group_sync_upd_work(struct work_struct *work)