Re: [PATCH] staging: wilc1000: fix infinite loop and out-of-bounds access

[Ajay Singh <ajay.kathat@microchip.com>]

Reviewed-by: Ajay Singh <ajay.kathat@microchip.com>

On Mon, 30 Apr 2018 07:50:40 -0500
"Gustavo A. R. Silva" <gustavo@embeddedor.com> wrote:

> If i < slot_id is initially true then it will remain true. Also,
> as i is being decremented it will end up accessing memory out of
> bounds.
> 
> Fix this by incrementing *i* instead of decrementing it.

Nice catch!
Thanks for submitting the changes.

> 
> Addresses-Coverity-ID: 1468454 ("Infinite loop")
> Fixes: faa657641081 ("staging: wilc1000: refactor scan() to free
> kmalloc memory on failure cases")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> 
> BTW... at first sight it seems to me that variables slot_id
> and i should be of type unsigned instead of signed.

Yes, 'slot_id' & 'i' can be changed to unsigned int.

> 
>  drivers/staging/wilc1000/wilc_wfi_cfgoperations.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/wilc1000/wilc_wfi_cfgoperations.c
> b/drivers/staging/wilc1000/wilc_wfi_cfgoperations.c index
> 3ca0c97..67104e8 100644 ---
> a/drivers/staging/wilc1000/wilc_wfi_cfgoperations.c +++
> b/drivers/staging/wilc1000/wilc_wfi_cfgoperations.c @@ -608,7
> +608,7 @@ wilc_wfi_cfg_alloc_fill_ssid(struct cfg80211_scan_request
> *request, out_free:
>  
> -	for (i = 0; i < slot_id ; i--)
> +	for (i = 0; i < slot_id; i++)
>  		kfree(ntwk->net_info[i].ssid);
>  
>  	kfree(ntwk->net_info);



Regards,
Ajay