diff mbox series

clk: Skip clk provider registration when np is NULL

Message ID 20210423191236.265996-1-tudor.ambarus@microchip.com (mailing list archive)
State Awaiting Upstream, archived
Headers show
Series clk: Skip clk provider registration when np is NULL | expand

Commit Message

Tudor Ambarus April 23, 2021, 7:12 p.m. UTC
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(+)

Comments

Tudor Ambarus April 23, 2021, 7:16 p.m. UTC | #1
On 4/23/21 10:12 PM, Tudor Ambarus wrote:
> 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
s/of_clk_add_provider()/of_clk_add_hw_provider()
> 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) {
>
Stephen Boyd April 24, 2021, 1:17 a.m. UTC | #2
Quoting Tudor Ambarus (2021-04-23 12:12:36)
> 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>
> ---

Please don't send patches as replies to previous threads. It makes it
harder to find the patch at a glance of all threads.

It also seems to be a

Fixes: 3c9ea42802a1 ("clk: Mark fwnodes when their clock provider is added/removed")

so can you please have both Fixes tags?

> 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.

With the Fixes tag updated please send To: gregkh@ to pick up as the
problematic patch (6579c8d97ad7) is in the driver tree and not the clk
tree, and add my tag

Reviewed-by: Stephen Boyd <sboyd@kernel.org>
diff mbox series

Patch

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) {