Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] rtlwifi: rtl_pci: Fix problem of too small skb->len
To:     "ian.schram" <ian.schram@telenet.be>, kvalo@codeaurora.org
Cc:     linux-wireless@vger.kernel.org, pkshih@realtek.com,
        Stable <stable@vger.kernel.org>
References: <20191019190222.29681-1-Larry.Finger@lwfinger.net>
 <05f25c80-51a9-bfad-ea4a-3c17b0eecf64@telenet.be>
From:   Larry Finger <Larry.Finger@lwfinger.net>
Message-ID: <20649f24-6412-4fac-f640-c611916aa85c@lwfinger.net>
Date:   Sat, 19 Oct 2019 20:13:39 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.1.1
MIME-Version: 1.0
In-Reply-To: <05f25c80-51a9-bfad-ea4a-3c17b0eecf64@telenet.be>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On 10/19/19 5:23 PM, ian.schram wrote:
> Hi,
> 
> 
> This patch doesn't appear to do anything? The increased length is not actually
> used, is a part of the patch missing?
> 
> 
> ps: superficial reading, i am not hampered by any specific knowledge of this 
> driver.
> 
> On 2019-10-19 21:02, Larry Finger wrote:
>> In commit 8020919a9b99 ("mac80211: Properly handle SKB with radiotap
>> only"), buffers whose length is too short cause a WARN_ON(1) to be
>> executed. This change exposed a fault in rtlwifi drivers, which is fixed
>> by increasing the length of the affected buffer before it is sent to
>> mac80211.
>>
>> Cc: Stable <stable@vger.kernel.org> # v5.0+
>> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
>> ---
>>
>> Kalle,
>>
>> Please send to v5.4.
>>
>> Larry
>> ---
>>
>>   drivers/net/wireless/realtek/rtlwifi/pci.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/net/wireless/realtek/rtlwifi/pci.c 
>> b/drivers/net/wireless/realtek/rtlwifi/pci.c
>> index 6087ec7a90a6..bb5144b7c64f 100644
>> --- a/drivers/net/wireless/realtek/rtlwifi/pci.c
>> +++ b/drivers/net/wireless/realtek/rtlwifi/pci.c
>> @@ -692,7 +692,10 @@ static void _rtl_pci_rx_to_mac80211(struct ieee80211_hw *hw,
>>           dev_kfree_skb_any(skb);
>>       } else {
>>           struct sk_buff *uskb = NULL;
>> +        int len = skb->len;
>> +        if (unlikely(len <= FCS_LEN))
>> +            len = FCS_LEN + 2;
>>           uskb = dev_alloc_skb(skb->len + 128);
>>           if (likely(uskb)) {
>>               memcpy(IEEE80211_SKB_RXCB(uskb), &rx_status,
>>

Ian,

Yes, I debugged using a different tree and missed one use of the new len. V2 
submitted.

Thanks for noticing.

Larry