Re: [PATCH] ath10k: htt_rx: Fix signedness bug in ath10k_update_per_peer_tx_stats

From: Anilkumar Kolli <akolli@codeaurora.org>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Ben Greear <greearb@candelatech.com>,
	Kalle Valo <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-wireless-owner@vger.kernel.org
Subject: Re: [PATCH] ath10k: htt_rx: Fix signedness bug in ath10k_update_per_peer_tx_stats
Date: Mon, 08 Oct 2018 12:08:06 +0530	[thread overview]
Message-ID: <af44d03892b3d51df391760af7af0382@codeaurora.org> (raw)
In-Reply-To: <fcc51fdd-fc31-9d2c-2e68-4ceecbb86129@embeddedor.com>

On 2018-10-06 00:45, Gustavo A. R. Silva wrote:
> On 10/5/18 9:14 PM, Gustavo A. R. Silva wrote:
>> 
>> 
>> On 10/5/18 9:09 PM, Ben Greear wrote:
>>> On 10/05/2018 11:42 AM, Gustavo A. R. Silva wrote:
>>>> Currently, the error handling for the call to function
>>>> ath10k_get_legacy_rate_idx() doesn't work because
>>>> *rate_idx* is of type u8 (8 bits, unsigned), which
>>>> makes it impossible for it to hold a value less
>>>> than 0.
>>>> 
>>>> Fix this by changing the type of variable *rate_idx*
>>>> to s8 (8 bits, signed).
>>> 
>>> There are more than 127 rates, are you sure this is doing
>>> what you want?
>>> 
>> 
>> Based on the following function, rate_idx can only hold values from 0 
>> to 11
>> 
> 
> ... and of course -EINVAL too
> 
>> static inline int ath10k_get_legacy_rate_idx(struct ath10k *ar, u8 
>> rate)
>> {
>>         static const u8 legacy_rates[] = {1, 2, 5, 11, 6, 9, 12,
>>                                           18, 24, 36, 48, 54};
>>         int i;
>> 
>>         for (i = 0; i < ARRAY_SIZE(legacy_rates); i++) {
>>                 if (rate == legacy_rates[i])
>>                         return i;
>>         }
>> 
>>         ath10k_warn(ar, "Invalid legacy rate %hhd peer stats", rate);
>>         return -EINVAL;
>> }
>> 
>> Thanks
>> --
>> Gustavo
>> 
>>> Thanks,
>>> Ben
>>> 
>>>> 
>>>> Addresses-Coverity-ID: 1473914 ("Unsigned compared against 0")
>>>> Fixes: 0189dbd71cbd ("ath10k: get the legacy rate index to update 
>>>> the txrate table")
>>>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>>>> ---
>>>>  drivers/net/wireless/ath/ath10k/htt_rx.c | 3 ++-
>>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>> 
>>>> diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c 
>>>> b/drivers/net/wireless/ath/ath10k/htt_rx.c
>>>> index f240525..edd0e74 100644
>>>> --- a/drivers/net/wireless/ath/ath10k/htt_rx.c
>>>> +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c
>>>> @@ -2753,7 +2753,8 @@ ath10k_update_per_peer_tx_stats(struct ath10k 
>>>> *ar,
>>>>                  struct ath10k_per_peer_tx_stats *peer_stats)
>>>>  {
>>>>      struct ath10k_sta *arsta = (struct ath10k_sta *)sta->drv_priv;
>>>> -    u8 rate = 0, rate_idx = 0, sgi;
>>>> +    u8 rate = 0, sgi;
>>>> +    s8 rate_idx = 0;
>>>>      struct rate_info txrate;
>>>> 
>>>>      lockdep_assert_held(&ar->data_lock);
>>>> 
>>> 
>>> 

I have sent a patch to address this,
https://patchwork.kernel.org/patch/10611943/

Thanks
Anil.