linux-kernel - [PATCH v3 1/1] i3c: fix refcount inconsistency in i3c_master

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Message-Id: <20251016143814.2551256-1-Frank.Li@nxp.com>
Date: Thu, 16 Oct 2025 10:38:13 -0400
From: Frank Li <Frank.Li@....com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Boris Brezillon <bbrezillon@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-i3c@...ts.infradead.org (moderated list:I3C SUBSYSTEM),
	linux-kernel@...r.kernel.org (open list)
Cc: markus.elfring@....de,
	imx@...ts.linux.dev
Subject: [PATCH v3 1/1] i3c: fix refcount inconsistency in i3c_master_register

In `i3c_master_register`, a possible refcount inconsistency has been
identified, causing possible resource leak.

Function `of_node_get` increases the refcount of `parent->of_node`. If
function `i3c_bus_init` fails, the function returns immediately without
a corresponding decrease, resulting in an inconsistent refcounter.

Move call i3c_bus_init() after device_initialize() to let callback
i3c_masterdev_release() release of_node.

Reported-by: Shuhao Fu <sfual@....ust.hk>
Closes: https://lore.kernel.org/linux-i3c/aO2tjp_FsV_WohPG@osx.local/T/#m2c05a982beeb14e7bf039c1d8db856734bf234c7
Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Signed-off-by: Frank Li <Frank.Li@....com>
---
Change in v3:
- add fixes tags

Change in v2:
- use i3c_masterdev_release() to put of_node to align other error path

v1 by Shuhao Fu <sfual@....ust.hk>

https://lore.kernel.org/linux-i3c/aO2tjp_FsV_WohPG@osx.local/T/#m2c05a982beeb14e7bf039c1d8db856734bf234c7
---
 drivers/i3c/master.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 2ef898a8fd806..8efec085d396c 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2811,10 +2811,6 @@ int i3c_master_register(struct i3c_master_controller *master,
 	INIT_LIST_HEAD(&master->boardinfo.i2c);
 	INIT_LIST_HEAD(&master->boardinfo.i3c);
 
-	ret = i3c_bus_init(i3cbus, master->dev.of_node);
-	if (ret)
-		return ret;
-
 	device_initialize(&master->dev);
 	dev_set_name(&master->dev, "i3c-%d", i3cbus->id);
 
@@ -2822,6 +2818,10 @@ int i3c_master_register(struct i3c_master_controller *master,
 	master->dev.coherent_dma_mask = parent->coherent_dma_mask;
 	master->dev.dma_parms = parent->dma_parms;
 
+	ret = i3c_bus_init(i3cbus, master->dev.of_node);
+	if (ret)
+		goto err_put_dev;
+
 	ret = of_populate_i3c_bus(master);
 	if (ret)
 		goto err_put_dev;
-- 
2.34.1