Re: [PATCH] ath9k_htc: fix potential out of bounds access with invalid rxstatus->rs_keyix

[Oleksij Rempel <linux@rempel-privat.de>]

Am 11.04.22 um 09:54 schrieb Dan Carpenter:
> On Sat, Apr 09, 2022 at 09:53:53AM +0200, Oleksij Rempel wrote:
>>> diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
>>> index 6a850a0bfa8a..a23eaca0326d 100644
>>> --- a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
>>> +++ b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
>>> @@ -1016,6 +1016,14 @@ static bool ath9k_rx_prepare(struct ath9k_htc_priv *priv,
>>>    		goto rx_next;
>>>    	}
>>>
>>> +	if (rxstatus->rs_keyix >= ATH_KEYMAX &&
>>> +	    rxstatus->rs_keyix != ATH9K_RXKEYIX_INVALID) {
>>> +		ath_dbg(common, ANY,
>>> +			"Invalid keyix, dropping (keyix: %d)\n",
>>> +			rxstatus->rs_keyix);
>>> +		goto rx_next;
>>> +	}
>>> +
>>>    	/* Get the RX status information */
>>>
>>>    	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));
>>
>> Looks ok to me.
>
> Thanks!
>
>>
>> By the way, rs_keyix seems to have a wrong type. It is declared as u8, but used as s8.
>
> That sounds like something outside the scope of the patch...

ack :)

> Why do you mean "used as s8"?  Which function are you talking about?
>
> You made me panic briefly because ATH9K_RXKEYIX_INVALID is a u8 so it
> needs to be u8.  I would have thought instinctively that u8 would be the
> right type for an index like this.

Because ATH_KEYMAX == S8_MAX and ATH9K_RXKEYIX_INVALID is ((u8)-1)

All bitmap values within drivers/net/wireless/ath should never have BIT(7) set, except it is -1.

--
Regards,
Oleksij