nvmem: core: fix device node refcounting

In of_nvmem_cell_get(), of_get_next_parent() is used on cell_np. This
will decrement the refcount on cell_np, but cell_np is still used later
in the code. Use of_get_parent() instead and of_node_put() in the
appropriate places.

Fixes: 69aba794 ("nvmem: Add a simple NVMEM framework for consumers")
Fixes: 7ae6478b ("nvmem: core: rework nvmem cell instance creation")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230127104015.23839-8-srinivas.kandagatla@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/core.c

@@ -1237,16 +1237,21 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
 	if (!cell_np)
 		return ERR_PTR(-ENOENT);
 
-	nvmem_np = of_get_next_parent(cell_np);
-	if (!nvmem_np)
+	nvmem_np = of_get_parent(cell_np);
+	if (!nvmem_np) {
+		of_node_put(cell_np);
 		return ERR_PTR(-EINVAL);
+	}
 
 	nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
 	of_node_put(nvmem_np);
-	if (IS_ERR(nvmem))
+	if (IS_ERR(nvmem)) {
+		of_node_put(cell_np);
 		return ERR_CAST(nvmem);
+	}
 
 	cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
+	of_node_put(cell_np);
 	if (!cell_entry) {
 		__nvmem_device_put(nvmem);
 		return ERR_PTR(-ENOENT);