Commit 61dd8a8a authored Jun 12, 2017 by Emmanuel Grumbach Committed by Luca Coelho Jul 21, 2017

iwlwifi: mvm: fix a NULL pointer dereference of error in recovery



Sometimes, we can have an firmware crash while trying to
recover from a previous firmware problem.
When that happens, lots of things can go wrong. For example
the stations don't get added properly to mvm->fw_id_to_mac_id.

Mac80211 tries to stop A-MPDU upon reconfig but in case of
a firmware crash we will bail out fairly early and in the
end, we won't delete the A-MPDU Rx timeout.
When that timer expired after a double firmware crash,
we end up dereferencing mvm->fw_id_to_mac_id[sta_id]
which is NULL.

Fixes: 10b2b201 ("iwlwifi: mvm: add infrastructure for tracking BA session in driver")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

parent f6eac740

drivers/net/wireless/intel/iwlwifi/mvm/sta.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -277,6 +277,18 @@ static void iwl_mvm_rx_agg_session_expired(unsigned long data)

		/* Timer expired */
		sta = rcu_dereference(ba_data->mvm->fw_id_to_mac_id[ba_data->sta_id]);

		/*
		* sta should be valid unless the following happens:
		* The firmware asserts which triggers a reconfig flow, but
		* the reconfig fails before we set the pointer to sta into
		* the fw_id_to_mac_id pointer table. Mac80211 can't stop
		* A-MDPU and hence the timer continues to run. Then, the
		* timer expires and sta is NULL.
		*/
		if (!sta)
		goto unlock;

		mvm_sta = iwl_mvm_sta_from_mac80211(sta);
		ieee80211_stop_rx_ba_session_offl(mvm_sta->vif,
		sta->addr, ba_data->tid);