linux-kernel - [PATCH] drivers: Fix reference leak in altr_sysmgr_regmap_lookup_by

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Message-Id: <20251025142352.25475-1-make24@iscas.ac.cn>
Date: Sat, 25 Oct 2025 22:23:52 +0800
From: Ma Ke <make24@...as.ac.cn>
To: lee@...nel.org,
	suzuki.poulose@....com,
	broonie@...nel.org,
	mdf@...nel.org,
	wsa@...nel.org
Cc: linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	Ma Ke <make24@...as.ac.cn>,
	stable@...r.kernel.org
Subject: [PATCH] drivers: Fix reference leak in altr_sysmgr_regmap_lookup_by_phandle()

altr_sysmgr_regmap_lookup_by_phandle() utilizes
driver_find_device_by_of_node() which internally calls
driver_find_device() to locate the matching device.
driver_find_device() increments the ref count of the found device by
calling get_device(), but altr_sysmgr_regmap_lookup_by_phandle() fails
to call put_device() to decrement the reference count before
returning. This results in a reference count leak of the device, which
may prevent the device from being properly released and cause a memory
leak.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: cfba5de9b99f ("drivers: Introduce device lookup variants by of_node")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 drivers/mfd/altera-sysmgr.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/altera-sysmgr.c b/drivers/mfd/altera-sysmgr.c
index fb5f988e61f3..c6c763fb7bbe 100644
--- a/drivers/mfd/altera-sysmgr.c
+++ b/drivers/mfd/altera-sysmgr.c
@@ -98,6 +98,7 @@ struct regmap *altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
 	struct device *dev;
 	struct altr_sysmgr *sysmgr;
 	struct device_node *sysmgr_np;
+	struct regmap *regmap;
 
 	if (property)
 		sysmgr_np = of_parse_phandle(np, property, 0);
@@ -116,8 +117,10 @@ struct regmap *altr_sysmgr_regmap_lookup_by_phandle(struct device_node *np,
 		return ERR_PTR(-EPROBE_DEFER);
 
 	sysmgr = dev_get_drvdata(dev);
+	regmap = sysmgr->regmap;
+	put_device(dev);
 
-	return sysmgr->regmap;
+	return regmap;
 }
 EXPORT_SYMBOL_GPL(altr_sysmgr_regmap_lookup_by_phandle);
 
-- 
2.17.1