[PATCH v2] drm/panthor: Fix access to uninitialized variable in tick_ctx_cleanup()

[Boris Brezillon]

The group variable can't be used to retrieve ptdev in our second loop,
because it points to the previously iterated list_head, not a valid
group. Get the ptdev object from the scheduler instead.

Cc: <stable at vger.kernel.org>
Fixes: d72f049087d4 ("drm/panthor: Allow driver compilation")
Reported-by: kernel test robot <lkp at intel.com>
Reported-by: Julia Lawall <julia.lawall at inria.fr>
Closes: https://lore.kernel.org/r/202409302306.UDikqa03-lkp@intel.com/
Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
---
 drivers/gpu/drm/panthor/panthor_sched.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
index 201d5e7a921e..24ff91c084e4 100644
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -2052,6 +2052,7 @@ static void
 tick_ctx_cleanup(struct panthor_scheduler *sched,
 		 struct panthor_sched_tick_ctx *ctx)
 {
+	struct panthor_device *ptdev = sched->ptdev;
 	struct panthor_group *group, *tmp;
 	u32 i;
 
@@ -2060,7 +2061,7 @@ tick_ctx_cleanup(struct panthor_scheduler *sched,
 			/* If everything went fine, we should only have groups
 			 * to be terminated in the old_groups lists.
 			 */
-			drm_WARN_ON(&group->ptdev->base, !ctx->csg_upd_failed_mask &&
+			drm_WARN_ON(&ptdev->base, !ctx->csg_upd_failed_mask &&
 				    group_can_run(group));
 
 			if (!group_can_run(group)) {
@@ -2083,7 +2084,7 @@ tick_ctx_cleanup(struct panthor_scheduler *sched,
 		/* If everything went fine, the groups to schedule lists should
 		 * be empty.
 		 */
-		drm_WARN_ON(&group->ptdev->base,
+		drm_WARN_ON(&ptdev->base,
 			    !ctx->csg_upd_failed_mask && !list_empty(&ctx->groups[i]));
 
 		list_for_each_entry_safe(group, tmp, &ctx->groups[i], run_node) {
-- 
2.46.0