[PATCH v2 06/14] drm/v3d: Reject invalid syncobj handles in submit ioctls

[Maíra Canal <mcanal@igalia.com>]

drm_sched_job_add_syncobj_dependency() returns -ENOENT both when the
handle is zero and when the handle is non-zero but does not find a
corresponding existing syncobj (userspace bug). The driver previously
ignored -ENOENT in both cases, silently accepting broken handles.

Distinguish the two: skip the call entirely when the handle is zero, as
there is no dependency, and let -ENOENT propagate for non-zero handles
that don't resolve, turning the error into a proper return to userspace.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
---
 drivers/gpu/drm/v3d/v3d_submit.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c
index f9231a87b963..30cb94ee1a2a 100644
--- a/drivers/gpu/drm/v3d/v3d_submit.c
+++ b/drivers/gpu/drm/v3d/v3d_submit.c
@@ -171,12 +171,11 @@ v3d_job_add_syncobjs(struct v3d_job *job, struct drm_file *file_priv,
 	int ret = 0;
 
 	if (!has_multisync) {
-		ret = drm_sched_job_add_syncobj_dependency(&job->base, file_priv,
-							   in_sync, 0);
-		// TODO: Investigate why this was filtered out for the IOCTL.
-		if (ret && ret != -ENOENT)
-			return ret;
-		return 0;
+		/* Ignore syncobj if its handle is zero */
+		if (in_sync)
+			ret = drm_sched_job_add_syncobj_dependency(&job->base, file_priv,
+								   in_sync, 0);
+		return ret;
 	}
 
 	if (se->in_sync_count && se->wait_stage == queue) {
@@ -190,11 +189,13 @@ v3d_job_add_syncobjs(struct v3d_job *job, struct drm_file *file_priv,
 				return -EFAULT;
 			}
 
-			ret = drm_sched_job_add_syncobj_dependency(&job->base,
-								   file_priv, in.handle, 0);
-			// TODO: Investigate why this was filtered out for the IOCTL.
-			if (ret && ret != -ENOENT)
-				return ret;
+			/* Ignore syncobj if its handle is zero */
+			if (in.handle) {
+				ret = drm_sched_job_add_syncobj_dependency(&job->base,
+									   file_priv, in.handle, 0);
+				if (ret)
+					return ret;
+			}
 		}
 	}
 

-- 
2.54.0