[PATCH] iwlwifi: eeprom-parse: use struct_size() in kzalloc()

[PATCH] iwlwifi: eeprom-parse: use struct_size() in kzalloc()

[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 = kzalloc(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 = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/wireless/intel/iwlwifi/iwl-eeprom-parse.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-eeprom-parse.c b/drivers/net/wireless/intel/iwlwifi/iwl-eeprom-parse.c
index 75940ac406b9..04338c3a6205 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-eeprom-parse.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-eeprom-parse.c
@@ -850,8 +850,7 @@ iwl_parse_eeprom_data(struct device *dev, const struct iwl_cfg *cfg,
 	if (WARN_ON(!cfg || !cfg->eeprom_params))
 		return NULL;
 
-	data = kzalloc(sizeof(*data) +
-		       sizeof(struct ieee80211_channel) * IWL_NUM_CHANNELS,
+	data = kzalloc(struct_size(data, channels, IWL_NUM_CHANNELS),
 		       GFP_KERNEL);
 	if (!data)
 		return NULL;
-- 
2.20.1

Re: [PATCH] iwlwifi: eeprom-parse: use struct_size() in kzalloc()

[Luciano Coelho]

On Tue, 2019-01-08 at 11:17 -0600, Gustavo A. R. Silva wrote:
> 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 = kzalloc(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 = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---

Applied to our internal tree, thanks! It will reach the mainline
following our normal upstreaming process.

--
Luca.

Re: [PATCH] iwlwifi: eeprom-parse: use struct_size() in kzalloc()

[Gustavo A. R. Silva]

On 1/22/19 4:58 AM, Luciano Coelho wrote:
> On Tue, 2019-01-08 at 11:17 -0600, Gustavo A. R. Silva wrote:
>> 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 = kzalloc(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 = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
>>
>> This code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>> ---
> 
> Applied to our internal tree, thanks! It will reach the mainline
> following our normal upstreaming process.
> 

Great. :)

Thanks, Luca.

--
Gustavo