From: Greg Kroah-Hartman gregkh@linuxfoundation.org

debugfs can now report an error code if something went wrong instead of just NULL. So if the return value is to be used as a "real" dentry, it needs to be checked if it is an error before dereferencing it.

This is now happening because of ff9fb72bc077 ("debugfs: return error values, not NULL"). If multiple iwlwifi devices are in the system, this can cause problems when the driver attempts to create the main debugfs directory again. Later on in the code we fail horribly by trying to dereference a pointer that is an error value.

Reported-by: Laura Abbott labbott@redhat.com Reported-by: Gabriel Ramirez gabriello.ramirez@gmail.com Cc: Johannes Berg johannes.berg@intel.com Cc: Emmanuel Grumbach emmanuel.grumbach@intel.com Cc: Luca Coelho luciano.coelho@intel.com Cc: Intel Linux Wireless linuxwifi@intel.com Cc: Kalle Valo kvalo@codeaurora.org Cc: stable stable@vger.kernel.org # 5.0 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Luca Coelho luciano.coelho@intel.com --- drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c index 2453ceabf00d..738eddb2e7ac 100644 --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c @@ -774,6 +774,11 @@ void iwl_mvm_vif_dbgfs_register(struct iwl_mvm *mvm, struct ieee80211_vif *vif) return;

mvmvif->dbgfs_dir = debugfs_create_dir("iwlmvm", dbgfs_dir); + if (IS_ERR_OR_NULL(mvmvif->dbgfs_dir)) { + IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n", + dbgfs_dir); + return; + }

if (!mvmvif->dbgfs_dir) { IWL_ERR(mvm, "Failed to create debugfs directory under %pd\n",