[PATCH] m68k: let clk_enable() return immediately if clk is NULL

[PATCH] m68k: let clk_enable() return immediately if clk is NULL

[Defang Bo]

Similar to commit<742859adc721>("m68k: let clk_disable() return immediately if clk is NULL").
there should be a check for clk to prevent NULL pointer dereference.

Signed-off-by: Defang Bo <bodefang@126.com>
---
 arch/m68k/coldfire/clk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/m68k/coldfire/clk.c b/arch/m68k/coldfire/clk.c
index 7bc666e..6decd11 100644
--- a/arch/m68k/coldfire/clk.c
+++ b/arch/m68k/coldfire/clk.c
@@ -90,6 +90,9 @@ EXPORT_SYMBOL(clk_get);
 int clk_enable(struct clk *clk)
 {
 	unsigned long flags;
+	if (!clk)
+		return -EINVAL;
+
 	spin_lock_irqsave(&clk_lock, flags);
 	if ((clk->enabled++ == 0) && clk->clk_ops)
 		clk->clk_ops->enable(clk);
-- 
2.7.4

Re: [PATCH] m68k: let clk_enable() return immediately if clk is NULL

[Geert Uytterhoeven]

Hi Defang,

On Mon, Dec 28, 2020 at 3:08 AM Defang Bo <bodefang@126.com> wrote:
> Similar to commit<742859adc721>("m68k: let clk_disable() return immediately if clk is NULL").
> there should be a check for clk to prevent NULL pointer dereference.
>
> Signed-off-by: Defang Bo <bodefang@126.com>

Thanks for your patch!

> --- a/arch/m68k/coldfire/clk.c
> +++ b/arch/m68k/coldfire/clk.c
> @@ -90,6 +90,9 @@ EXPORT_SYMBOL(clk_get);
>  int clk_enable(struct clk *clk)
>  {
>         unsigned long flags;

Please keep the blank line between variable declarations and
statements (no complaint from scripts/checkpatch.pl? See
Documentation/process/submitting-patches.rst
).

> +       if (!clk)
> +               return -EINVAL;
> +
>         spin_lock_irqsave(&clk_lock, flags);
>         if ((clk->enabled++ == 0) && clk->clk_ops)
>                 clk->clk_ops->enable(clk);

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] m68k: let clk_enable() return immediately if clk is NULL

[Greg Ungerer]

Hi Defang,

On 28/12/20 12:07 pm, Defang Bo wrote:
> Similar to commit<742859adc721>("m68k: let clk_disable() return immediately if clk is NULL").
> there should be a check for clk to prevent NULL pointer dereference.
> 
> Signed-off-by: Defang Bo <bodefang@126.com>

I have applied this to the m68knommu git tree, for-next branch -
with blank line added as per Geert's suggestion.

Regards
Greg



> ---
>   arch/m68k/coldfire/clk.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/arch/m68k/coldfire/clk.c b/arch/m68k/coldfire/clk.c
> index 7bc666e..6decd11 100644
> --- a/arch/m68k/coldfire/clk.c
> +++ b/arch/m68k/coldfire/clk.c
> @@ -90,6 +90,9 @@ EXPORT_SYMBOL(clk_get);
>   int clk_enable(struct clk *clk)
>   {
>   	unsigned long flags;
> +	if (!clk)
> +		return -EINVAL;
> +
>   	spin_lock_irqsave(&clk_lock, flags);
>   	if ((clk->enabled++ == 0) && clk->clk_ops)
>   		clk->clk_ops->enable(clk);
>