[PATCH] clk: sunxi: Remove use of VLAIS

[PATCH] clk: sunxi: Remove use of VLAIS

[Stephen Boyd]

Using an array allocated on the stack may lead to stack overflows
and other problems. Furthermore, VLAIS doesn't work well with
LLVM compilers, so move the allocation to the heap and avoid the
use of VLAIS here.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
 drivers/clk/sunxi/clk-sun8i-mbus.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
index 3aaa9cbef791..8e7128e69823 100644
--- a/drivers/clk/sunxi/clk-sun8i-mbus.c
+++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
@@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
 static void __init sun8i_a23_mbus_setup(struct device_node *node)
 {
 	int num_parents = of_clk_get_parent_count(node);
-	const char *parents[num_parents];
+	const char **parents;
 	const char *clk_name = node->name;
 	struct resource res;
 	struct clk_divider *div;
@@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
 	void __iomem *reg;
 	int err;
 
+	parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
+	if (!parents)
+		return;
+
 	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
 	if (!reg) {
 		pr_err("Could not get registers for sun8i-mbus-clk\n");
-		return;
+		goto err_free_parents;
 	}
 
 	div = kzalloc(sizeof(*div), GFP_KERNEL);
@@ -107,6 +111,8 @@ err_free_div:
 	kfree(div);
 err_unmap:
 	iounmap(reg);
+err_free_parents:
+	kfree(parents);
 	of_address_to_resource(node, 0, &res);
 	release_mem_region(res.start, resource_size(&res));
 }
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Chen-Yu Tsai]

On Tue, Mar 1, 2016 at 4:20 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> Using an array allocated on the stack may lead to stack overflows
> and other problems. Furthermore, VLAIS doesn't work well with
> LLVM compilers, so move the allocation to the heap and avoid the
> use of VLAIS here.
>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
>  drivers/clk/sunxi/clk-sun8i-mbus.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
> index 3aaa9cbef791..8e7128e69823 100644
> --- a/drivers/clk/sunxi/clk-sun8i-mbus.c
> +++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
> @@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
>  static void __init sun8i_a23_mbus_setup(struct device_node *node)
>  {
>         int num_parents = of_clk_get_parent_count(node);
> -       const char *parents[num_parents];
> +       const char **parents;
>         const char *clk_name = node->name;
>         struct resource res;
>         struct clk_divider *div;
> @@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
>         void __iomem *reg;
>         int err;
>
> +       parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
> +       if (!parents)
> +               return;
> +
>         reg = of_io_request_and_map(node, 0, of_node_full_name(node));
>         if (!reg) {
>                 pr_err("Could not get registers for sun8i-mbus-clk\n");
> -               return;
> +               goto err_free_parents;
>         }
>
>         div = kzalloc(sizeof(*div), GFP_KERNEL);
> @@ -107,6 +111,8 @@ err_free_div:
>         kfree(div);
>  err_unmap:
>         iounmap(reg);
> +err_free_parents:
> +       kfree(parents);

AFAIK the CCF makes a deep copy of parents, so you should
always free it? I specifically checked it before using
VLAIS here.

ChenYu

>         of_address_to_resource(node, 0, &res);
>         release_mem_region(res.start, resource_size(&res));
>  }
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Stephen Boyd]

On 03/03, Chen-Yu Tsai wrote:
> On Tue, Mar 1, 2016 at 4:20 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> >         div = kzalloc(sizeof(*div), GFP_KERNEL);
> > @@ -107,6 +111,8 @@ err_free_div:
> >         kfree(div);
> >  err_unmap:
> >         iounmap(reg);
> > +err_free_parents:
> > +       kfree(parents);
> 
> AFAIK the CCF makes a deep copy of parents, so you should
> always free it? I specifically checked it before using
> VLAIS here.
> 

Yes. Good catch. Here's the update.

--8<---
From: Stephen Boyd <sboyd@codeaurora.org>
Subject: [PATCH] clk: sunxi: Remove use of VLAIS

Using an array allocated on the stack may lead to stack overflows
and other problems. Furthermore, VLAIS doesn't work well with
LLVM compilers, so move the allocation to the heap and avoid the
use of VLAIS here.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
 drivers/clk/sunxi/clk-sun8i-mbus.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
index 3aaa9cbef791..90acc8549d60 100644
--- a/drivers/clk/sunxi/clk-sun8i-mbus.c
+++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
@@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
 static void __init sun8i_a23_mbus_setup(struct device_node *node)
 {
 	int num_parents = of_clk_get_parent_count(node);
-	const char *parents[num_parents];
+	const char **parents;
 	const char *clk_name = node->name;
 	struct resource res;
 	struct clk_divider *div;
@@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
 	void __iomem *reg;
 	int err;
 
+	parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
+	if (!parents)
+		return;
+
 	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
 	if (!reg) {
 		pr_err("Could not get registers for sun8i-mbus-clk\n");
-		return;
+		goto err_free_parents;
 	}
 
 	div = kzalloc(sizeof(*div), GFP_KERNEL);
@@ -90,6 +94,7 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
 	if (err)
 		goto err_unregister_clk;
 
+	kfree(parents); /* parents is deep copied */
 	/* The MBUS clocks needs to be always enabled */
 	__clk_get(clk);
 	clk_prepare_enable(clk);
@@ -107,6 +112,8 @@ err_free_div:
 	kfree(div);
 err_unmap:
 	iounmap(reg);
+err_free_parents:
+	kfree(parents);
 	of_address_to_resource(node, 0, &res);
 	release_mem_region(res.start, resource_size(&res));
 }
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Maxime Ripard]

[-- Attachment #1: Type: text/plain, Size: 3104 bytes --]

Hi,

On Thu, Mar 03, 2016 at 11:16:04AM -0800, Stephen Boyd wrote:
> On 03/03, Chen-Yu Tsai wrote:
> > On Tue, Mar 1, 2016 at 4:20 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> > >         div = kzalloc(sizeof(*div), GFP_KERNEL);
> > > @@ -107,6 +111,8 @@ err_free_div:
> > >         kfree(div);
> > >  err_unmap:
> > >         iounmap(reg);
> > > +err_free_parents:
> > > +       kfree(parents);
> > 
> > AFAIK the CCF makes a deep copy of parents, so you should
> > always free it? I specifically checked it before using
> > VLAIS here.
> > 
> 
> Yes. Good catch. Here's the update.
> 
> --8<---
> From: Stephen Boyd <sboyd@codeaurora.org>
> Subject: [PATCH] clk: sunxi: Remove use of VLAIS

VLAIS?

> Using an array allocated on the stack may lead to stack overflows
> and other problems. Furthermore, VLAIS doesn't work well with
> LLVM compilers, so move the allocation to the heap and avoid the
> use of VLAIS here.
> 
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
>  drivers/clk/sunxi/clk-sun8i-mbus.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
> index 3aaa9cbef791..90acc8549d60 100644
> --- a/drivers/clk/sunxi/clk-sun8i-mbus.c
> +++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
> @@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
>  static void __init sun8i_a23_mbus_setup(struct device_node *node)
>  {
>  	int num_parents = of_clk_get_parent_count(node);
> -	const char *parents[num_parents];
> +	const char **parents;
>  	const char *clk_name = node->name;
>  	struct resource res;
>  	struct clk_divider *div;
> @@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
>  	void __iomem *reg;
>  	int err;
>  
> +	parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
> +	if (!parents)
> +		return;
> +
>  	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
>  	if (!reg) {
>  		pr_err("Could not get registers for sun8i-mbus-clk\n");
> -		return;
> +		goto err_free_parents;
>  	}
>  
>  	div = kzalloc(sizeof(*div), GFP_KERNEL);
> @@ -90,6 +94,7 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
>  	if (err)
>  		goto err_unregister_clk;
>  
> +	kfree(parents); /* parents is deep copied */
>  	/* The MBUS clocks needs to be always enabled */
>  	__clk_get(clk);
>  	clk_prepare_enable(clk);
> @@ -107,6 +112,8 @@ err_free_div:
>  	kfree(div);
>  err_unmap:
>  	iounmap(reg);
> +err_free_parents:
> +	kfree(parents);
>  	of_address_to_resource(node, 0, &res);
>  	release_mem_region(res.start, resource_size(&res));

The error path is wrong here, if you jump here from a failing call to
of_io_request_and_map, you'll end up releasing a memory region which
is not requested.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Stephen Boyd]

On 03/04, Maxime Ripard wrote:
> On Thu, Mar 03, 2016 at 11:16:04AM -0800, Stephen Boyd wrote:
> > From: Stephen Boyd <sboyd@codeaurora.org>
> > Subject: [PATCH] clk: sunxi: Remove use of VLAIS
> 
> VLAIS?

Hmm I guess it's just VLA, so llvm won't break. I'll reword
commit text.

> 
> > @@ -107,6 +112,8 @@ err_free_div:
> >  	kfree(div);
> >  err_unmap:
> >  	iounmap(reg);
> > +err_free_parents:
> > +	kfree(parents);
> >  	of_address_to_resource(node, 0, &res);
> >  	release_mem_region(res.start, resource_size(&res));
> 
> The error path is wrong here, if you jump here from a failing call to
> of_io_request_and_map, you'll end up releasing a memory region which
> is not requested.
> 

Oh right. Let's hope third time is the last.

---8<---
From: Stephen Boyd <sboyd@codeaurora.org>
Subject: [PATCH] clk: sunxi: Remove use of variable length array

Using an array allocated on the stack may lead to stack overflows
and other problems so let's move the allocation to the heap
instead. This silences the following checker warning as well.

drivers/clk/sunxi/clk-sun8i-mbus.c:36:29: warning: Variable length array is used.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
 drivers/clk/sunxi/clk-sun8i-mbus.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
index 3aaa9cbef791..411d3033a96e 100644
--- a/drivers/clk/sunxi/clk-sun8i-mbus.c
+++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
@@ -33,7 +33,7 @@ static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
 static void __init sun8i_a23_mbus_setup(struct device_node *node)
 {
 	int num_parents = of_clk_get_parent_count(node);
-	const char *parents[num_parents];
+	const char **parents;
 	const char *clk_name = node->name;
 	struct resource res;
 	struct clk_divider *div;
@@ -43,10 +43,14 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
 	void __iomem *reg;
 	int err;
 
+	parents = kcalloc(num_parents, sizeof(*parents), GFP_KERNEL);
+	if (!parents)
+		return;
+
 	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
 	if (!reg) {
 		pr_err("Could not get registers for sun8i-mbus-clk\n");
-		return;
+		goto err_free_parents;
 	}
 
 	div = kzalloc(sizeof(*div), GFP_KERNEL);
@@ -90,6 +94,7 @@ static void __init sun8i_a23_mbus_setup(struct device_node *node)
 	if (err)
 		goto err_unregister_clk;
 
+	kfree(parents); /* parents is deep copied */
 	/* The MBUS clocks needs to be always enabled */
 	__clk_get(clk);
 	clk_prepare_enable(clk);
@@ -109,5 +114,7 @@ err_unmap:
 	iounmap(reg);
 	of_address_to_resource(node, 0, &res);
 	release_mem_region(res.start, resource_size(&res));
+err_free_parents:
+	kfree(parents);
 }
 CLK_OF_DECLARE(sun8i_a23_mbus, "allwinner,sun8i-a23-mbus-clk", sun8i_a23_mbus_setup);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Maxime Ripard]

[-- Attachment #1: Type: text/plain, Size: 1643 bytes --]

On Fri, Mar 04, 2016 at 09:18:41AM -0800, Stephen Boyd wrote:
> On 03/04, Maxime Ripard wrote:
> > On Thu, Mar 03, 2016 at 11:16:04AM -0800, Stephen Boyd wrote:
> > > From: Stephen Boyd <sboyd@codeaurora.org>
> > > Subject: [PATCH] clk: sunxi: Remove use of VLAIS
> > 
> > VLAIS?
> 
> Hmm I guess it's just VLA, so llvm won't break. I'll reword
> commit text.
> 
> > 
> > > @@ -107,6 +112,8 @@ err_free_div:
> > >  	kfree(div);
> > >  err_unmap:
> > >  	iounmap(reg);
> > > +err_free_parents:
> > > +	kfree(parents);
> > >  	of_address_to_resource(node, 0, &res);
> > >  	release_mem_region(res.start, resource_size(&res));
> > 
> > The error path is wrong here, if you jump here from a failing call to
> > of_io_request_and_map, you'll end up releasing a memory region which
> > is not requested.
> > 
> 
> Oh right. Let's hope third time is the last.
> 
> ---8<---
> From: Stephen Boyd <sboyd@codeaurora.org>
> Subject: [PATCH] clk: sunxi: Remove use of variable length array
> 
> Using an array allocated on the stack may lead to stack overflows
> and other problems so let's move the allocation to the heap
> instead. This silences the following checker warning as well.
> 
> drivers/clk/sunxi/clk-sun8i-mbus.c:36:29: warning: Variable length array is used.
> 
> Cc: Chen-Yu Tsai <wens@csie.org>
> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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Re: [PATCH] clk: sunxi: Remove use of VLAIS

[Stephen Boyd]

On 03/08, Maxime Ripard wrote:
> On Fri, Mar 04, 2016 at 09:18:41AM -0800, Stephen Boyd wrote:
> > Oh right. Let's hope third time is the last.
> > 
> > ---8<---
> > From: Stephen Boyd <sboyd@codeaurora.org>
> > Subject: [PATCH] clk: sunxi: Remove use of variable length array
> > 
> > Using an array allocated on the stack may lead to stack overflows
> > and other problems so let's move the allocation to the heap
> > instead. This silences the following checker warning as well.
> > 
> > drivers/clk/sunxi/clk-sun8i-mbus.c:36:29: warning: Variable length array is used.
> > 
> > Cc: Chen-Yu Tsai <wens@csie.org>
> > Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> 
> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> 

Applied to clk-next.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project