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

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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: 10b2b2019d ("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>
This commit is contained in:
Emmanuel Grumbach 2017-06-12 15:10:09 +03:00 committed by Luca Coelho
parent f6eac740a9
commit 61dd8a8a6a
1 changed files with 12 additions and 0 deletions
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12
drivers/net/wireless/intel/iwlwifi/mvm/sta.c
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@ -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);