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SubjectRe: [PATCH] iwlwifi: properly check debugfs dentry before using it
On Sat, 2019-03-30 at 10:31 +0100, Greg Kroah-Hartman wrote:
> 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>
> 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>
>
>
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> index 2453ceabf00d..6925527d8457 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/debugfs-vif.c
> @@ -774,8 +774,7 @@ 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 (!mvmvif->dbgfs_dir) {
> + if (IS_ERR_OR_NULL(mvmvif->dbgfs_dir)) {
> IWL_ERR(mvm, "Failed to create debugfs directory under
> %pd\n",
> dbgfs_dir);
> return;

Thanks! I've applied this internally and will send upstream for v5.1-
rc* following our normal upstreaming process.

I added the other Reported-by that Laura asked for and added "mvm:" to
the subject.

--
Cheers,
Luca.

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