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drm/sun4i: tcon-top: Use struct_size() in devm_kzalloc()

PATCH Applied Gustavo A. R. Silva 3 participants 3 messages Aug 24, 2018

Subsystems (5)
DRM drivers DRM misc Arm/Allwinner sunXi SoC support DRM drivers for Allwinner A10 +1 more subsystems
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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 drm/sun4i: tcon-top: Use struct_size() in devm_kzalloc()

One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example:

struct foo {
	int stuff;
        void *entry[];
};

instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/gpu/drm/sun4i/sun8i_tcon_top.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/gpu/drm/sun4i/sun8i_tcon_top.c +1 -2
index 55fe398..3040a79 100644
@@ -129,8 +129,7 @@ static int sun8i_tcon_top_bind(struct device *dev, struct device *master,
 	if (!tcon_top)
 		return -ENOMEM;
 
-	clk_data = devm_kzalloc(dev, sizeof(*clk_data) +
-				sizeof(*clk_data->hws) * CLK_NUM,
+	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, CLK_NUM),
 				GFP_KERNEL);
 	if (!clk_data)
 		return -ENOMEM;
Signature · 1 line
2.7.4
Reviewed-by on v1 1/1
#1 lore raw
Quoted 11 lines · Gustavo A. R. Silva

One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example:

struct foo {
        int stuff;
        void *entry[];
};

instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Quoted 8 lines

Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
Reviewed-by Kees Cook <[email protected]>

-Kees

Quoted 21 lines
---
 drivers/gpu/drm/sun4i/sun8i_tcon_top.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/gpu/drm/sun4i/sun8i_tcon_top.c +1 -3
index 55fe398..3040a79 100644
@@ -129,8 +129,7 @@ static int sun8i_tcon_top_bind(struct device *dev, struct device *master,
        if (!tcon_top)
                return -ENOMEM;
 
-       clk_data = devm_kzalloc(dev, sizeof(*clk_data) +
-                               sizeof(*clk_data->hws) * CLK_NUM,
+       clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, CLK_NUM),
                                GFP_KERNEL);
        if (!clk_data)
                return -ENOMEM;
--

2.7.4

Signature · 2 lines
Kees Cook
Pixel Security
Applied
#2 lore raw
Quoted 16 lines · Kees Cook
Quoted 14 lines · Gustavo A. R. Silva

One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example:

struct foo {
        int stuff;
        void *entry[];
};

instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:

Quoted 7 lines
Quoted 5 lines

instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>
Reviewed-by Kees Cook <[email protected]>

Applied, thanks!
Maxime

Signature · 3 lines
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com