[PATCH v10 5/5] drm/panthor: Fix race condition when gathering fdinfo group samples

["Adrián Larumbe" <adrian.larumbe@collabora.com>]

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.

Fixes: e16635d88fa0 ("drm/panthor: add DRM fdinfo support")
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.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 f3c6ca4dc11c..6d49b4f40f58 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)
-- 
2.47.1