drm/mediatek: Add missing IS_ERR check for ovl_adaptor platform devicegrafted

platform_device_register_data() can fail and return an ERR_PTR, but the
return value is used without checking, leading to an invalid pointer
being stored in ddp_comp[].dev and passed to component_match_add() and
mtk_ddp_comp_init(), which could result in a kernel crash.

Add an IS_ERR() check to jump to the error handling path on failure.

Fixes: 0d9eee9118b7 ("drm/mediatek: Add drm ovl_adaptor sub driver for MT8195")
Cc: stable@vger.kernel.org
Signed-off-by: Haojie Li <lihaojie@kylinos.cn>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260825100845.438893-1-lihaojie@kylinos.cn/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
new file mode 100644
index 000000000..92a9f243c
--- /dev/null
+++ b/lib/iommu-helper.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IOMMU helper functions for the free area management
+ */
+
+#include <linux/bitmap.h>
+#include <linux/iommu-helper.h>
+
+unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
+			       unsigned long start, unsigned int nr,
+			       unsigned long shift, unsigned long boundary_size,
+			       unsigned long align_mask)
+{
+	unsigned long index;
+
+	/* We don't want the last of the limit */
+	size -= 1;
+again:
+	index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
+	if (index < size) {
+		if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
+			start = ALIGN(shift + index, boundary_size) - shift;
+			goto again;
+		}
+		bitmap_set(map, index, nr);
+		return index;
+	}
+	return -1;
+}