linux-kernel - [PATCH v2] Bluetooth: btbcm: fix missing of_node_put() in btbcm_get_board

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Message-Id: <20241031-bluetooth-btbcm-node-cleanup-v2-1-482d52910bfa@gmail.com>
Date: Thu, 31 Oct 2024 13:11:23 +0100
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Marcel Holtmann <marcel@...tmann.org>, 
 Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
 Linus Walleij <linus.walleij@...aro.org>
Cc: linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: [PATCH v2] Bluetooth: btbcm: fix missing of_node_put() in
 btbcm_get_board_name()

of_find_node_by_path() returns a pointer to a device_node with its
refcount incremented, and a call to of_node_put() is required to
decrement the refcount again and avoid leaking the resource.

If 'of_property_read_string_index(root, "compatible", 0, &tmp)' fails,
the function returns without calling of_node_put(root) before doing so.

The automatic cleanup attribute can be used by means of the __free()
macro to automatically call of_node_put() when the variable goes out of
scope, fixing the issue and also accounting for new error paths.

Fixes: 63fac3343b99 ("Bluetooth: btbcm: Support per-board firmware variants")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
Changes in v2:
- Squash patches for mainline solution without intermediate steps.
- Link to v1: https://lore.kernel.org/r/20241030-bluetooth-btbcm-node-cleanup-v1-0-fdc4b9df9fe3@gmail.com
---
 drivers/bluetooth/btbcm.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/bluetooth/btbcm.c b/drivers/bluetooth/btbcm.c
index eef00467905e..a1153ada74d2 100644
--- a/drivers/bluetooth/btbcm.c
+++ b/drivers/bluetooth/btbcm.c
@@ -541,11 +541,10 @@ static const struct bcm_subver_table bcm_usb_subver_table[] = {
 static const char *btbcm_get_board_name(struct device *dev)
 {
 #ifdef CONFIG_OF
-	struct device_node *root;
+	struct device_node *root __free(device_node) = of_find_node_by_path("/");
 	char *board_type;
 	const char *tmp;
 
-	root = of_find_node_by_path("/");
 	if (!root)
 		return NULL;
 
@@ -555,7 +554,6 @@ static const char *btbcm_get_board_name(struct device *dev)
 	/* get rid of any '/' in the compatible string */
 	board_type = devm_kstrdup(dev, tmp, GFP_KERNEL);
 	strreplace(board_type, '/', '-');
-	of_node_put(root);
 
 	return board_type;
 #else

---
base-commit: 6fb2fa9805c501d9ade047fc511961f3273cdcb5
change-id: 20241030-bluetooth-btbcm-node-cleanup-23d21a73870c

Best regards,
-- 
Javier Carrasco <javier.carrasco.cruz@...il.com>