Re: [PATCH] iwlwifi: fix use-after-free

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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On Tue, Feb 08, 2022 at 11:47:30AM +0100, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> If no firmware was present at all (or, presumably, all of the
> firmware files failed to parse), we end up unbinding by calling
> device_release_driver(), which calls remove(), which then in
> iwlwifi calls iwl_drv_stop(), freeing the 'drv' struct. However
> the new code I added will still erroneously access it after it
> was freed.
> 
> Set 'failure=false' in this case to avoid the access, all data
> was already freed anyway.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Stefan Agner <stefan@agner.ch>
> Reported-by: Wolfgang Walter <linux@stwm.de>
> Reported-by: Jason Self <jason@bluehome.net>
> Reported-by: Dominik Behr <dominik@dominikbehr.com>
> Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
> Fixes: ab07506b0454 ("iwlwifi: fix leaks/bad data after failed firmware load")
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

Thanks!

> ---
>  drivers/net/wireless/intel/iwlwifi/iwl-drv.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-drv.c b/drivers/net/wireless/intel/iwlwifi/iwl-drv.c
> index 83e3b731ad29..6651e78b39ec 100644
> --- a/drivers/net/wireless/intel/iwlwifi/iwl-drv.c
> +++ b/drivers/net/wireless/intel/iwlwifi/iwl-drv.c
> @@ -1707,6 +1707,8 @@ static void iwl_req_fw_callback(const struct firmware *ucode_raw, void *context)
>   out_unbind:
>  	complete(&drv->request_firmware_complete);
>  	device_release_driver(drv->trans->dev);
> +	/* drv has just been freed by the release */
> +	failure = false;
>   free:
>  	if (failure)
>  		iwl_dealloc_ucode(drv);
> -- 
> 2.34.1
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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