Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 10 Feb 2021 13:54:57 +0300
From:   Dan Carpenter <dan.carpenter@oracle.com>
To:     avraham.stern@intel.com
Cc:     linux-wireless@vger.kernel.org
Subject: [bug report] iwlwifi: mvm: toggle tx antenna if tx fails during
 connection establishment
Message-ID: <YCO7gahK0ktH8YkY@mwanda>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Precedence: bulk

[ Sorry, I don't know why Smatch is warning about a three year old bug
  and I'm not sure that it's blaming the correct commit but the warning
  looks correct.  - dan ]

Hello Avraham Stern,

This is a semi-automatic email about new static checker warnings.

The patch 0dde2440a77f: "iwlwifi: mvm: toggle tx antenna if tx fails
during connection establishment" from Jul 11, 2018, leads to the
following Smatch complaint:

    drivers/net/wireless/intel/iwlwifi/mvm/tx.c:356 iwl_mvm_set_tx_cmd_rate()
    error: we previously assumed 'sta' could be null (see line 341)

drivers/net/wireless/intel/iwlwifi/mvm/tx.c
   340	
   341		if (ieee80211_is_data(fc) && sta) {
                                             ^^^
This assumes that "sta" can be NULL.

   342			struct iwl_mvm_sta *mvmsta = iwl_mvm_sta_from_mac80211(sta);
   343	
   344			if (mvmsta->sta_state >= IEEE80211_STA_AUTHORIZED) {
   345				tx_cmd->initial_rate_index = 0;
   346				tx_cmd->tx_flags |= cpu_to_le32(TX_CMD_FLG_STA_RATE);
   347				return;
   348			}
   349		} else if (ieee80211_is_back_req(fc)) {
   350			tx_cmd->tx_flags |=
   351				cpu_to_le32(TX_CMD_FLG_ACK | TX_CMD_FLG_BAR);
   352		}
   353	
   354		/* Set the rate in the TX cmd */
   355		tx_cmd->rate_n_flags =
   356			cpu_to_le32(iwl_mvm_get_tx_rate_n_flags(mvm, info, sta, fc));
                                                                           ^^^
It is dereferenced unconsiditionally inside the function.

   357	}
   358	

See also:
drivers/net/wireless/intel/iwlwifi/mvm/tx.c:486 iwl_mvm_set_tx_params() error: we previously assumed 'sta' could be null (see line 482)

regards,
dan carpenter