Re: [PATCH next] wifi: iwlwifi: Fix uninitialized variable with __free()

[Jeff Johnson <jeff.johnson@oss.qualcomm.com>]

On 3/12/2025 8:24 AM, Dan Carpenter wrote:
> On Wed, Mar 12, 2025 at 08:15:18AM -0700, Jeff Johnson wrote:
>> On 3/12/2025 1:31 AM, Dan Carpenter wrote:
>>> Pointers declared with the __free(kfree) attribute need to be initialized
>>> because they will be passed to kfree() on every return path.  There are
>>> two return statement before the "cmd" pointer is initialized so this
>>> leads to an uninitialized variable bug.
>>>
>>> Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
>>> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
>>> ---
>>>  drivers/net/wireless/intel/iwlwifi/mld/debugfs.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/wireless/intel/iwlwifi/mld/debugfs.c b/drivers/net/wireless/intel/iwlwifi/mld/debugfs.c
>>> index c759c5c68dc0..1d4b2ad5d388 100644
>>> --- a/drivers/net/wireless/intel/iwlwifi/mld/debugfs.c
>>> +++ b/drivers/net/wireless/intel/iwlwifi/mld/debugfs.c
>>> @@ -556,8 +556,8 @@ iwl_dbgfs_vif_twt_setup_write(struct iwl_mld *mld, char *buf, size_t count,
>>>  	};
>>>  	struct ieee80211_vif *vif = data;
>>>  	struct iwl_mld_vif *mld_vif = iwl_mld_vif_from_mac80211(vif);
>>> +	struct iwl_dhc_cmd *cmd __free(kfree) = NULL;
>>
>> hmm, I thought the recommended convention was to define __free() pointers at
>> the point of allocation. cleanup.h explicitly says:
>>
>>  * Given that the "__free(...) = NULL" pattern for variables defined at
>>  * the top of the function poses this potential interdependency problem
>>  * the recommendation is to always define and assign variables in one
>>  * statement and not group variable definitions at the top of the
>>  * function when __free() is used.
>>
> 
> People do it either way.  I'm agnostic so long as it doesn't have bugs.

I've been doing it with the allocation since that's what Linus said he wanted:

https://lore.kernel.org/all/CAHk-=whO1+-4ALjFWSE0kzytz1kEbWPvy3xWvcUP1dJ4t-QqkA@mail.gmail.com/

But this patch is already in wireless-next, so it's moot now.