(bug report) iwlwifi: inconsitent NULL checking

[Dan Carpenter <dan.carpenter@oracle.com>]

[ All old wireless warnings are showing up as new because the files
  moved around in linux-next.  - dan ]

Hello Johannes Berg,

The patch 8ca151b568b6: "iwlwifi: add the MVM driver" from Jan 24,
2013, leads to the following static checker warning:

	drivers/net/wireless/intel/iwlwifi/mvm/rs.c:2802 rs_get_rate()
	error: we previously assumed 'lq_sta' could be null (see line 2793)

drivers/net/wireless/intel/iwlwifi/mvm/rs.c
  2790          /* TODO: handle rate_idx_mask and rate_idx_mcs_mask */
  2791  
  2792          /* Treat uninitialized rate scaling data same as non-existing. */
  2793          if (lq_sta && !lq_sta->pers.drv) {
                    ^^^^^^
Check.

  2794                  IWL_DEBUG_RATE(mvm, "Rate scaling not initialized yet.\n");
  2795                  mvm_sta = NULL;
  2796          }
  2797  
  2798          /* Send management frames and NO_ACK data using lowest rate. */
  2799          if (rate_control_send_low(sta, mvm_sta, txrc))
  2800                  return;
  2801  
  2802          iwl_mvm_hwrate_to_tx_rate(lq_sta->last_rate_n_flags,
                                          ^^^^^^^^^^^^^^^^^^^^^^^^^
Uchecked dereference.

  2803                                    info->band, &info->control.rates[0]);
  2804          info->control.rates[0].count = 1;
  2805  

See also:
drivers/net/wireless/intel/iwlwifi/dvm/rs.c:2742 rs_get_rate() error: we previously assumed 'lq_sta' could be null (see line 2733)


regards,
dan carpenter