[PATCH 4/4] regulator: tps6594: Fix device node reference leaks in multiphase loop

[Uday Khare <udaykhare77@gmail.com>]

In tps6594_regulator_probe(), the multi-phase configuration loop calls
of_find_node_by_name() to find buck nodes by name, and of_get_parent()
twice to navigate to the PMIC parent node. None of the acquired node
references (np, intermediate parent, np_pmic_parent) are ever released
via of_node_put(), causing a reference leak on every loop iteration.

Additionally, of_find_node_by_name() can return NULL, but the result was
immediately passed to of_node_full_name() and of_get_parent() without a
NULL check, which could lead to a NULL pointer dereference.

Fix this by:
- Adding a NULL check for np after of_find_node_by_name()
- Storing the intermediate parent node in a local variable np_parent
- Calling of_node_put() on np, np_parent and np_pmic_parent at the
  end of each loop iteration

Fixes: f17ccc5deb4d ("regulator: tps6594-regulator: Add driver for TI TPS6594 regulators")
Signed-off-by: Uday Khare <udaykhare77@gmail.com>
---
 drivers/regulator/tps6594-regulator.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/tps6594-regulator.c b/drivers/regulator/tps6594-regulator.c
index 645e83462c64..31a5218d5510 100644
--- a/drivers/regulator/tps6594-regulator.c
+++ b/drivers/regulator/tps6594-regulator.c
@@ -669,13 +669,20 @@ static int tps6594_regulator_probe(struct platform_device *pdev)
 	 * buck_configured to avoid creating bucks for every buck in multiphase
 	 */
 	for (multi = 0; multi < desc->num_multi_phase_regs; multi++) {
+		struct device_node *np_parent;
+
 		multi_regs = &desc->multi_phase_regs[multi];
 		np = of_find_node_by_name(tps->dev->of_node, multi_regs->supply_name);
-		npname = of_node_full_name(np);
-		np_pmic_parent = of_get_parent(of_get_parent(np));
-		if (of_node_cmp(of_node_full_name(np_pmic_parent), tps->dev->of_node->full_name))
+		if (!np)
 			continue;
-		if (strcmp(npname, multi_regs->supply_name) == 0) {
+
+		npname = of_node_full_name(np);
+		np_parent = of_get_parent(np);
+		np_pmic_parent = of_get_parent(np_parent);
+
+		if (np_pmic_parent &&
+		    !of_node_cmp(of_node_full_name(np_pmic_parent), tps->dev->of_node->full_name) &&
+		    strcmp(npname, multi_regs->supply_name) == 0) {
 			switch (multi) {
 			case MULTI_BUCK12:
 				buck_multi[0] = true;
@@ -706,6 +713,10 @@ static int tps6594_regulator_probe(struct platform_device *pdev)
 				break;
 			}
 		}
+
+		of_node_put(np_pmic_parent);
+		of_node_put(np_parent);
+		of_node_put(np);
 	}
 
 	reg_irq_nb = desc->num_irq_types * (desc->num_buck_regs + desc->num_ldo_regs);
-- 
2.54.0