[PATCH v2] clk: check ops pointer on clock register

[PATCH v2] clk: check ops pointer on clock register

[Jerome Brunet]

Nothing really prevents a provider from (trying to) register a clock
without providing the clock ops structure.

We do check the individual fields before using them, but not the
structure pointer itself. This may have the usual nasty consequences when
the pointer is dereferenced, most likely when checking one the field
during the initialization.

This is fixed by returning an error on clock register if the ops pointer
is NULL.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
Changes since v1:
 * Add WARN_ON so the error cannot be silently ignored
 * Remove fixes tag

 drivers/clk/clk.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 8a1860a36c77..211f97e8dc65 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2683,7 +2683,13 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 		ret = -ENOMEM;
 		goto fail_name;
 	}
+
+	if (WARN_ON(!hw->init->ops)) {
+		ret = -EINVAL;
+		goto fail_ops;
+	}
 	core->ops = hw->init->ops;
+
 	if (dev && pm_runtime_enabled(dev))
 		core->dev = dev;
 	if (dev && dev->driver)
@@ -2745,6 +2751,7 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 		kfree_const(core->parent_names[i]);
 	kfree(core->parent_names);
 fail_parent_names:
+fail_ops:
 	kfree_const(core->name);
 fail_name:
 	kfree(core);
-- 
2.14.3

Re: [PATCH v2] clk: check ops pointer on clock register

[Michael Turquette]

Quoting Jerome Brunet (2017-12-19 00:33:29)
> Nothing really prevents a provider from (trying to) register a clock
> without providing the clock ops structure.
> 
> We do check the individual fields before using them, but not the
> structure pointer itself. This may have the usual nasty consequences when
> the pointer is dereferenced, most likely when checking one the field
> during the initialization.
> 
> This is fixed by returning an error on clock register if the ops pointer
> is NULL.
> 
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Applied to clk-check-ops-ptr

Regards,
Mike

> ---
> Changes since v1:
>  * Add WARN_ON so the error cannot be silently ignored
>  * Remove fixes tag
> 
>  drivers/clk/clk.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 8a1860a36c77..211f97e8dc65 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -2683,7 +2683,13 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
>                 ret = -ENOMEM;
>                 goto fail_name;
>         }
> +
> +       if (WARN_ON(!hw->init->ops)) {
> +               ret = -EINVAL;
> +               goto fail_ops;
> +       }
>         core->ops = hw->init->ops;
> +
>         if (dev && pm_runtime_enabled(dev))
>                 core->dev = dev;
>         if (dev && dev->driver)
> @@ -2745,6 +2751,7 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
>                 kfree_const(core->parent_names[i]);
>         kfree(core->parent_names);
>  fail_parent_names:
> +fail_ops:
>         kfree_const(core->name);
>  fail_name:
>         kfree(core);
> -- 
> 2.14.3
>