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memory: atmel-ebi: Use struct_size() in devm_kzalloc()

PATCH Applied Gustavo A. R. Silva 3 participants 3 messages Aug 24, 2018 – Aug 27, 2018

Subsystems (2)
Arm/Microchip (AT91) SoC support Memory controller drivers
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Gustavo A. R. Silva

author
#0 lore raw

PATCH 1/1 memory: atmel-ebi: 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/memory/atmel-ebi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/memory/atmel-ebi.c +1 -2
index b907865..c3748b4 100644
@@ -327,8 +327,7 @@ static int atmel_ebi_dev_setup(struct atmel_ebi *ebi, struct device_node *np,
 		return -EINVAL;
 	}
 
-	ebid = devm_kzalloc(ebi->dev,
-			    sizeof(*ebid) + (numcs * sizeof(*ebid->configs)),
+	ebid = devm_kzalloc(ebi->dev, struct_size(ebid, configs, numcs),
 			    GFP_KERNEL);
 	if (!ebid)
 		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/memory/atmel-ebi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/memory/atmel-ebi.c +1 -3
index b907865..c3748b4 100644
@@ -327,8 +327,7 @@ static int atmel_ebi_dev_setup(struct atmel_ebi *ebi, struct device_node *np,
                return -EINVAL;
        }
 
-       ebid = devm_kzalloc(ebi->dev,
-                           sizeof(*ebid) + (numcs * sizeof(*ebid->configs)),
+       ebid = devm_kzalloc(ebi->dev, struct_size(ebid, configs, numcs),
                            GFP_KERNEL);
        if (!ebid)
                return -ENOMEM;
--

2.7.4

Signature · 2 lines
Kees Cook
Pixel Security
maintainer Applied
#2 lore raw
In reply to Gustavo A. R. Silva
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 9 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]>
---
 drivers/memory/atmel-ebi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Applied, thanks.

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