linux-kernel - Re: [PATCH] staging: wicl1000: fix dereference after free in wilc_wlan

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Date:	Tue, 22 Sep 2015 15:04:17 +0200
From:	Javier Martinez Canillas <javier@....samsung.com>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
	Rachel Kim <rachel.kim@...el.com>,
	Chris Park <chris.park@...el.com>,
	linux-wireless@...r.kernel.org, Johnny Kim <johnny.kim@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Tony Cho <tony.cho@...el.com>, Leo Kim <leo.kim@...el.com>
Subject: Re: [PATCH] staging: wicl1000: fix dereference after free in
 wilc_wlan_cleanup()

Hello Sudip,

Thanks a lot for your feedback.

On 09/22/2015 02:16 PM, Sudip Mukherjee wrote:
> On Tue, Sep 22, 2015 at 12:24:50PM +0200, Javier Martinez Canillas wrote:
>> The wilc_wlan_cleanup() function iterates over the list of transmission
>> buffers freeing all of them and then iterates over the receive buffers
>> list to free all of them as well.
>>
>> But on the receive loop a pointer to struct txq_entry_t is dereferenced
>> instead of the pointer to a struct rxq_entry_t. This not only causes a
>> dereference to a pointer already freed but also leaks the memory in the
>> struct rxq_entry_t buffer.
>>
>> Fixes: c5c77ba18ea6 ("staging: wilc1000: Add SDIO/SPI 802.11 driver")
>> Signed-off-by: Javier Martinez Canillas <javier@....samsung.com>
>>
>> ---
>>
>>  drivers/staging/wilc1000/wilc_wlan.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/wilc1000/wilc_wlan.c b/drivers/staging/wilc1000/wilc_wlan.c
>> index 4c25179c2fec..c40f143b00b7 100644
>> --- a/drivers/staging/wilc1000/wilc_wlan.c
>> +++ b/drivers/staging/wilc1000/wilc_wlan.c
>> @@ -1746,7 +1746,7 @@ static void wilc_wlan_cleanup(void)
>>  		if (rqe == NULL)
>>  			break;
>>  #ifdef MEMORY_DYNAMIC
>> -		kfree(tqe->buffer);
>> +		kfree(rqe->buffer);
>>  #endif
> MEMORY_DYNAMIC is only used here and no where else. And buffer was
> allocated in the else part of #ifdef MEMORY_STATIC.
> So you should really be using #ifndef MEMORY_STATIC here instead of
> #ifdef MEMORY_DYNAMIC otherwise memory leak will still remain.
>

You are right that #ifndef MEMORY_STATIC should be used instead to fix
the memory leak. I'll post a v2 changing that as well.

> regards
> sudip
>

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America
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