[PATCH] mtd: maps: physmap: fix reference leak on failed device registration

[Guangshuo Li]

When platform_device_register() fails in physmap_init(), the embedded
struct device in physmap_flash has already been initialized by
device_initialize(), but the failure path only unregisters the platform
driver and does not drop the device reference for the current platform
device:

  physmap_init()
    -> platform_device_register(&physmap_flash)
       -> device_initialize(&physmap_flash.dev)
       -> setup_pdev_dma_masks(&physmap_flash)
       -> platform_device_add(&physmap_flash)

This leads to a reference leak when platform_device_register() fails.
Fix this by calling platform_device_put() before unregistering the
platform driver.

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

Fixes: 1ca5d2f0196cf ("mtd/maps/physmap: catch failure to register MTD_PHYSMAP_COMPAT device")
Cc: stable at vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244 at gmail.com>
---
 drivers/mtd/maps/physmap-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
index 0dcc25b7ff98..6299a741e65b 100644
--- a/drivers/mtd/maps/physmap-core.c
+++ b/drivers/mtd/maps/physmap-core.c
@@ -659,8 +659,10 @@ static int __init physmap_init(void)
 #ifdef CONFIG_MTD_PHYSMAP_COMPAT
 	if (err == 0) {
 		err = platform_device_register(&physmap_flash);
-		if (err)
+		if (err) {
+			platform_device_put(&physmap_flash);
 			platform_driver_unregister(&physmap_flash_driver);
+		}
 	}
 #endif
 
-- 
2.43.0