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([2601:602:9800:dae6::fa4a]) by smtp.gmail.com with ESMTPSA id w8sm5440314qki.54.2019.04.01.08.39.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 01 Apr 2019 08:39:28 -0700 (PDT) Subject: Re: [PATCH] iwlwifi: properly check debugfs dentry before using it To: Greg Kroah-Hartman , Luca Coelho Cc: linux-kernel@vger.kernel.org, Johannes Berg , Emmanuel Grumbach , Intel Linux Wireless , Kalle Valo , linux-wireless@vger.kernel.org, Luca Coelho , stable References: <20190122152151.16139-24-gregkh@linuxfoundation.org> <03bb68be-8e42-a463-2d57-3be051dc2016@redhat.com> <20190327012600.GA3649@kroah.com> <5660d50d-6cbf-3b36-6e6c-312b1617ed23@redhat.com> <20190327015346.GA17979@kroah.com> <5f9c8beda0e925b079aa9342ce1c9523659837a4.camel@coelho.fi> <20190330092247.GA14300@kroah.com> <20190330093152.GB14300@kroah.com> From: Laura Abbott Message-ID: <50bffbea-69b5-71f4-0b9c-aead1ffc54da@redhat.com> Date: Mon, 1 Apr 2019 08:39:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 MIME-Version: 1.0 In-Reply-To: <20190330093152.GB14300@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 3/30/19 2:31 AM, 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 Can you add Reported-by: Gabriel Ramirez for the bugzilla reporter who took the time to do the bisect? I'll ask for testing as well. > Cc: Johannes Berg > Cc: Emmanuel Grumbach > Cc: Luca Coelho > Cc: Intel Linux Wireless > Cc: Kalle Valo > Cc: stable # 5.0 > Signed-off-by: Greg Kroah-Hartman > > > 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; >