[PATCH v2] drm/imagination: Fix parameter validation in pvr_fw_object_destroy()

[Alexandru Dadu <alexandru.dadu@imgtec.com>]

Fix parameter validation to avoid possible NULL pointer dereference from
pvr_fw_object_destroy() when handling allocation failures.

Sashiko report:
If pvr_gem_object_create() fails in
pvr_fw_object_create_and_map_common(), fw_obj->gem is explicitly set to
NULL before jumping to the error cleanup path.
The cleanup path then calls pvr_fw_object_destroy().

Potential kernel panic when calling pvr_fw_object_destroy() with a NULL
fw_obj->gem.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/dri-devel/20260810132202.3C16D1F000E9@smtp.kernel.org/
Fixes: cc1aeedb98ad ("drm/imagination: Implement firmware infrastructure and META FW support")
Signed-off-by: Alexandru Dadu <alexandru.dadu@imgtec.com>
---
Changes in v2:
- Commit message and cover letter updates.
- Link to v1: https://patch.msgid.link/20260812-fix-null-pointer-dereference-v1-1-f69b2ffe9520@imgtec.com
---
 drivers/gpu/drm/imagination/pvr_fw.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/imagination/pvr_fw.c b/drivers/gpu/drm/imagination/pvr_fw.c
index 850a3ec8e775..88f11fb01304 100644
--- a/drivers/gpu/drm/imagination/pvr_fw.c
+++ b/drivers/gpu/drm/imagination/pvr_fw.c
@@ -1425,22 +1425,26 @@ pvr_fw_object_create_and_map_offset(struct pvr_device *pvr_dev,
  */
 void pvr_fw_object_destroy(struct pvr_fw_object *fw_obj)
 {
-	struct pvr_gem_object *pvr_obj = fw_obj->gem;
-	struct drm_gem_object *gem_obj = gem_from_pvr_gem(pvr_obj);
-	struct pvr_device *pvr_dev = to_pvr_device(gem_obj->dev);
+	if (!fw_obj)
+		return;
 
-	mutex_lock(&pvr_dev->fw_dev.fw_objs.lock);
-	list_del(&fw_obj->node);
-	mutex_unlock(&pvr_dev->fw_dev.fw_objs.lock);
+	if (fw_obj->gem) {
+		struct pvr_gem_object *pvr_obj = fw_obj->gem;
+		struct drm_gem_object *gem_obj = gem_from_pvr_gem(pvr_obj);
+		struct pvr_device *pvr_dev = to_pvr_device(gem_obj->dev);
 
-	if (drm_mm_node_allocated(&fw_obj->fw_mm_node)) {
-		/* If we can't unmap, leak the memory. */
-		if (WARN_ON(pvr_fw_object_fw_unmap(fw_obj)))
-			return;
-	}
+		mutex_lock(&pvr_dev->fw_dev.fw_objs.lock);
+		list_del(&fw_obj->node);
+		mutex_unlock(&pvr_dev->fw_dev.fw_objs.lock);
+
+		if (drm_mm_node_allocated(&fw_obj->fw_mm_node)) {
+			/* If we can't unmap, leak the memory. */
+			if (WARN_ON(pvr_fw_object_fw_unmap(fw_obj)))
+				return;
+		}
 
-	if (fw_obj->gem)
 		pvr_gem_object_put(fw_obj->gem);
+	}
 
 	kfree(fw_obj);
 }

---
base-commit: bd4f284df04d76fd65e57141cb1e6e7a49e4c3cb
change-id: 20260812-fix-null-pointer-dereference-2c891142d988

Best regards,
--  
Alexandru Dadu <alexandru.dadu@imgtec.com>