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[73.202.202.92]) by smtp.gmail.com with ESMTPSA id x68sm8797538pfd.183.2019.09.21.18.40.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Sep 2019 18:40:12 -0700 (PDT) Date: Sat, 21 Sep 2019 18:40:09 -0700 From: Jakub Kicinski To: Allen Pais Cc: netdev@vger.kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers/net/fjes: fix a potential NULL pointer dereference Message-ID: <20190921184009.32edfa43@cakuba.netronome.com> In-Reply-To: <1568824395-4162-1-git-send-email-allen.pais@oracle.com> References: <1568824395-4162-1-git-send-email-allen.pais@oracle.com> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 18 Sep 2019 22:03:15 +0530, Allen Pais wrote: > alloc_workqueue is not checked for errors and as a result, > a potential NULL dereference could occur. > > Signed-off-by: Allen Pais If I'm looking at this right you are jumping to err_free_netdev without setting the err variable. It must had been set to 0 from the return of fjes_sw_init(). This means we will free the netdev, and return 0. This means probe will not fail and driver's remove function will be run at some point. fjes_remove it will try to free the netdev again. Looks like there's another existing bug here in that the work queues are not free when something fails in fjes_probe, just the netdev. Once you untangle that, and before you post a v2, could you please try to identify which commit introduced the regression and provide an appropriate "Fixes" tag? > diff --git a/drivers/net/fjes/fjes_main.c b/drivers/net/fjes/fjes_main.c > index bbbc1dc..2d04104 100644 > --- a/drivers/net/fjes/fjes_main.c > +++ b/drivers/net/fjes/fjes_main.c > @@ -1237,8 +1237,15 @@ static int fjes_probe(struct platform_device *plat_dev) > adapter->open_guard = false; > > adapter->txrx_wq = alloc_workqueue(DRV_NAME "/txrx", WQ_MEM_RECLAIM, 0); > + if (unlikely(!adapter->txrx_wq)) > + goto err_free_netdev; > + > adapter->control_wq = alloc_workqueue(DRV_NAME "/control", > WQ_MEM_RECLAIM, 0); > + if (unlikely(!adapter->control_wq)) { > + destroy_workqueue(adapter->txrx_wq); > + goto err_free_netdev; > + } > > INIT_WORK(&adapter->tx_stall_task, fjes_tx_stall_task); > INIT_WORK(&adapter->raise_intr_rxdata_task,