[PATCH] clk: Skip clk provider registration when np is NULL

Tudor Ambarus
2021-04-23T19:12:57Z

commit 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
revealed that clk/bcm/clk-raspberrypi.c driver calls
devm_of_clk_add_hw_provider(), with a NULL dev->of_node, which resulted in a
NULL pointer dereference in of_clk_add_provider() when calling
fwnode_dev_initialized().

Returning 0 is reducing the if conditions in driver code and is being
consistent with the CONFIG_OF=n inline stub that returns 0 when CONFIG_OF
is disabled. The downside is that drivers will maybe register clkdev lookups
when they don't need to and waste some memory.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
This would be the second approach, where we don't return an error when
one calls devm_of_clk_add_hw_provider with a NULL of_node, but instead
we just return 0 and skip the logic in the core and the drivers.

drivers/clk/clk.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index e2ec1b745243..5d10da3519ac 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -4540,6 +4540,9 @@ int of_clk_add_provider(struct device_node *np,
struct of_clk_provider *cp;
int ret;

+ if (!np)
+ return 0;
+
cp = kzalloc(sizeof(*cp), GFP_KERNEL);
if (!cp)
return -ENOMEM;
@@ -4579,6 +4582,9 @@ int of_clk_add_hw_provider(struct device_node *np,
struct of_clk_provider *cp;
int ret;

+ if (!np)
+ return 0;
+
cp = kzalloc(sizeof(*cp), GFP_KERNEL);
if (!cp)
return -ENOMEM;
@@ -4676,6 +4682,9 @@ void of_clk_del_provider(struct device_node *np)
{
struct of_clk_provider *cp;

+ if (!np)
+ return 0;
+
mutex_lock(&of_clk_mutex);
list_for_each_entry(cp, &of_clk_providers, link) {
if (cp->node == np) {
--
2.25.1