2019-01-08 17:20:10

by Gustavo A. R. Silva

Subject: [PATCH] iwlwifi: eeprom-parse: use struct_size() in 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 = 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 <[email protected]>
---
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

2019-01-22 10:59:56

by Luciano Coelho

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

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 <[email protected]>
> ---

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

--
Luca.

2019-01-29 16:52:05

by Gustavo A. R. Silva

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

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 <[email protected]>
>> ---
>
> Applied to our internal tree, thanks! It will reach the mainline
> following our normal upstreaming process.
>

Great. :)

Thanks, Luca.

--
Gustavo