linux-kernel - [PATCH v2 2/9] of/irq: Fix device node refcount leakage in API of_irq_parse

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Message-Id: <20250209-of_irq_fix-v2-2-93e3a2659aa7@quicinc.com>
Date: Sun, 09 Feb 2025 20:58:55 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
 Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, Marc Zyngier <maz@...nel.org>, 
 Stefan Wiehler <stefan.wiehler@...ia.com>, Tony Lindgren <tony@...mide.com>, 
 Thierry Reding <thierry.reding@...il.com>, 
 Benjamin Herrenschmidt <benh@...nel.crashing.org>, 
 Julia Lawall <Julia.Lawall@...6.fr>
Cc: Zijun Hu <zijun_hu@...oud.com>, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Zijun Hu <quic_zijuhu@...cinc.com>, 
 stable@...r.kernel.org
Subject: [PATCH v2 2/9] of/irq: Fix device node refcount leakage in API
 of_irq_parse_one()

From: Zijun Hu <quic_zijuhu@...cinc.com>

of_irq_parse_one(@int_gen_dev, i, ...) will leak refcount of @i_th_phandle

int_gen_dev {
    ...
    interrupts-extended = ..., <&i_th_phandle ...>, ...;
    ...
};

Refcount of @i_th_phandle is increased by of_parse_phandle_with_args()
but is not decreased by API of_irq_parse_one() before return, so causes
refcount leakage.

Fix by putting the node's refcount before return as the other branch does.
Also add comments about refcount of node @out_irq->np got by the API.

Fixes: 79d9701559a9 ("of/irq: create interrupts-extended property")
Cc: stable@...r.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
---
 drivers/of/irq.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 6c843d54ebb116132144e6300d6d7ce94e763cf8..d88719c316a3931502c34a65b2db8921f7528d99 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -339,6 +339,8 @@ EXPORT_SYMBOL_GPL(of_irq_parse_raw);
  * This function resolves an interrupt for a node by walking the interrupt tree,
  * finding which interrupt controller node it is attached to, and returning the
  * interrupt specifier that can be used to retrieve a Linux IRQ number.
+ *
+ * Note: refcount of node @out_irq->np is increased by 1 on success.
  */
 int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_args *out_irq)
 {
@@ -367,8 +369,11 @@ int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_ar
 	/* Try the new-style interrupts-extended first */
 	res = of_parse_phandle_with_args(device, "interrupts-extended",
 					"#interrupt-cells", index, out_irq);
-	if (!res)
-		return of_irq_parse_raw(addr_buf, out_irq);
+	if (!res) {
+		p = out_irq->np;
+		res = of_irq_parse_raw(addr_buf, out_irq);
+		goto out;
+	}
 
 	/* Look for the interrupt parent. */
 	p = of_irq_find_parent(device);

-- 
2.34.1