[PATCH] macintosh: adb: fix reference leak on failed platform device registration

[Guangshuo Li]

When platform_device_register() fails in adbdev_init(), the embedded
struct device in adb_pfdev has already been initialized by
device_initialize(), but the failure path does not drop the device
reference for the current platform device:

  adbdev_init()
    platform_device_register(&adb_pfdev)
      device_initialize(&adb_pfdev.dev)
      setup_pdev_dma_masks(&adb_pfdev)
      return platform_device_add(&adb_pfdev)

As documented in platform_device_register(), the caller must use
platform_device_put() to give up the reference initialized in this
function when registration fails.

This leads to a reference leak when platform_device_register() fails.
Fix this by checking the return value and calling platform_device_put().

The issue was identified by a static analysis tool I developed and
confirmed by manual review.

Fixes: c9f6d3d5c6d4f ("[POWERPC] adb: Replace sleep notifier with platform driver suspend/resume hooks")
Cc: stable at vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244 at gmail.com>
---
 drivers/macintosh/adb.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/macintosh/adb.c b/drivers/macintosh/adb.c
index fe150125e099..eff06f78aa80 100644
--- a/drivers/macintosh/adb.c
+++ b/drivers/macintosh/adb.c
@@ -883,6 +883,8 @@ adb_dummy_probe(struct platform_device *dev)
 static void __init
 adbdev_init(void)
 {
+	int err;
+
 	if (register_chrdev(ADB_MAJOR, "adb", &adb_fops)) {
 		pr_err("adb: unable to get major %d\n", ADB_MAJOR);
 		return;
@@ -893,6 +895,9 @@ adbdev_init(void)
 
 	device_create(&adb_dev_class, NULL, MKDEV(ADB_MAJOR, 0), NULL, "adb");
 
-	platform_device_register(&adb_pfdev);
+	err = platform_device_register(&adb_pfdev);
+	if (err)
+		platform_device_put(&adb_pfdev);
+
 	platform_driver_probe(&adb_pfdrv, adb_dummy_probe);
 }
-- 
2.43.0