From: Zijun Hu <quic_zijuhu@quicinc.com>

For macro for_each_child_of_node(parent, child), refcount of @child has
been increased before entering its loop body, so normally needs to call
of_node_put(@child) before returning from the loop body to avoid refcount
leakage.

of_phy_provider_lookup() has such usage but does not call of_node_put()
before returning, so cause leakage of the OF node refcount.

Fixed by simply calling of_node_put() before returning from the loop body.

The APIs affected by this issue are shown below since they indirectly
invoke problematic of_phy_provider_lookup().
phy_get()
of_phy_get()
devm_phy_get()
devm_of_phy_get()
devm_of_phy_get_by_index()

Fixes: 2a4c37016ca9 ("phy: core: Fix of_phy_provider_lookup to return PHY provider for sub node")
Cc: stable@vger.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>

---
The following kernel mainline commit fixes a similar issue:
Commit: b337cc3ce475 ("backlight: lm3509_bl: Fix early returns in for_each_child_of_node()")
---
 drivers/phy/phy-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index 967878b78797..de0264dfc387 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -145,8 +145,10 @@ static struct phy_provider *of_phy_provider_lookup(struct device_node *node)
 			return phy_provider;
 
 		for_each_child_of_node(phy_provider->children, child)
-			if (child == node)
+			if (child == node) {
+				of_node_put(child);
 				return phy_provider;
+			}
 	}
 
 	return ERR_PTR(-EPROBE_DEFER);

-- 
2.34.1

On Thu, Oct 24, 2024 at 10:39:30PM +0800, Zijun Hu wrote:
> From: Zijun Hu <quic_zijuhu@quicinc.com>
> 
> For macro for_each_child_of_node(parent, child), refcount of @child has
> been increased before entering its loop body, so normally needs to call
> of_node_put(@child) before returning from the loop body to avoid refcount
> leakage.
> 
> of_phy_provider_lookup() has such usage but does not call of_node_put()
> before returning, so cause leakage of the OF node refcount.
> 
> Fixed by simply calling of_node_put() before returning from the loop body.
> 
> The APIs affected by this issue are shown below since they indirectly
> invoke problematic of_phy_provider_lookup().
> phy_get()
> of_phy_get()
> devm_phy_get()
> devm_of_phy_get()
> devm_of_phy_get_by_index()
> 
> Fixes: 2a4c37016ca9 ("phy: core: Fix of_phy_provider_lookup to return PHY provider for sub node")
> Cc: stable@vger.kernel.org
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>

Looks good.

Reviewed-by: Johan Hovold <johan+linaro@kernel.org>