[PATCH v2] firmware_loader: fix device reference leak in firmware_upload_register()

[Guangshuo Li <lgs201920130244@gmail.com>]

firmware_upload_register()
  -> fw_create_instance()
     -> device_initialize()

After fw_create_instance() succeeds, the lifetime of the embedded struct
device is expected to be managed through the device core reference
counting, since fw_create_instance() has already called
device_initialize().

In firmware_upload_register(), if alloc_lookup_fw_priv() fails after
fw_create_instance() succeeds, the code reaches free_fw_sysfs and frees
fw_sysfs directly instead of releasing the device reference with
put_device(). This may leave the reference count of the embedded struct
device unbalanced, resulting in a refcount leak.

The issue was identified by a static analysis tool I developed and
confirmed by manual review. Fix this by using put_device(fw_dev) in the
failure path and letting fw_dev_release() handle the final cleanup,
instead of freeing the instance directly from the error path.

Fixes: 97730bbb242c ("firmware_loader: Add firmware-upload support")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/base/firmware_loader/sysfs_upload.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/base/firmware_loader/sysfs_upload.c b/drivers/base/firmware_loader/sysfs_upload.c
index f59a7856934c..a6dab34b22d8 100644
--- a/drivers/base/firmware_loader/sysfs_upload.c
+++ b/drivers/base/firmware_loader/sysfs_upload.c
@@ -351,7 +351,8 @@ firmware_upload_register(struct module *module, struct device *parent,
 	if (ret != 0) {
 		if (ret > 0)
 			ret = -EINVAL;
-		goto free_fw_sysfs;
+		put_device(fw_dev);
+		goto exit_module_put;
 	}
 	fw_priv->is_paged_buf = true;
 	fw_sysfs->fw_priv = fw_priv;
@@ -365,9 +366,6 @@ firmware_upload_register(struct module *module, struct device *parent,
 
 	return fw_upload;
 
-free_fw_sysfs:
-	kfree(fw_sysfs);
-
 free_fw_upload_priv:
 	kfree(fw_upload_priv);
 
-- 
2.43.0