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x-aligned-from=fail; x-cm=none score=0; x-ptr=fail x-ptr-helo=whitealder.osuosl.org x-ptr-lookup=smtp1.osuosl.org; x-return-mx=pass smtp.domain=linuxdriverproject.org smtp.result=pass smtp_is_org_domain=yes header.domain=oracle.com header.result=pass header_is_org_domain=yes; x-tls=pass version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128; x-vs=clean score=0 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfJB+8sZ/ZFbFrhTKLCwXASJ4XiJ5khAmM+B+ddJ08zHbKOiLVQIGHZ+FfT9Cr0M3hFRh8OJ01ugt5QhHwJ5hXy8mpbyA0tFH5nEyBMTK/EplNHYGdlwn fXSvKrntBQLcBL6a62YsU9E61wMDiNmzRyuJaMLDnBqjh2H+Fqm+gEwIFJd5Y3cmqjR/YwyHylyD+0bUcbk48pvoegSnYGlHQkL9U6f9hOwwISR9NkiYPqlz OWNnaUETPN6/HuLVsWYcVQ== X-CM-Analysis: v=2.3 cv=E8HjW5Vl c=1 sm=1 tr=0 a=28bQ1EhdAjTzU1YDPmtEKw==:117 a=28bQ1EhdAjTzU1YDPmtEKw==:17 a=kj9zAlcOel0A:10 a=Kd1tUaAdevIA:10 a=-uNXE31MpBQA:10 a=jJxKW8Ag-pUA:10 a=1XWaLZrsAAAA:8 a=DDOyTI_5AAAA:8 a=1aPI_1tQwmsEff5gB5sA:9 a=CjuIK1q_8ugA:10 a=_BcfOz0m4U4ohdxiHPKc:22 cc=dsc X-ME-CMScore: 0 X-ME-CMCategory: none X-Remote-Delivered-To: driverdev-devel@osuosl.org Date: Tue, 3 Apr 2018 13:40:52 +0300 From: Dan Carpenter To: Ji-Hun Kim Subject: Re: [PATCH v3] staging: vt6655: check for memory allocation failures Message-ID: <20180403104052.6wbomdguifrmlmpz@mwanda> References: <1522377844-23591-1-git-send-email-ji_hun.kim@samsung.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1522377844-23591-1-git-send-email-ji_hun.kim@samsung.com> User-Agent: NeoMutt/20170609 (1.8.3) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8851 signatures=668697 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1804030109 X-BeenThere: driverdev-devel@linuxdriverproject.org X-Mailman-Version: 2.1.24 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, y.k.oh@samsung.com, gregkh@linuxfoundation.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, julia.lawall@lip6.fr, baijiaju1990@gmail.com, forest@alittletooquiet.net, santhameena13@gmail.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Fri, Mar 30, 2018 at 11:44:04AM +0900, Ji-Hun Kim wrote: > @@ -528,18 +528,22 @@ static void device_free_rings(struct vnt_private *priv) > priv->tx0_bufs, priv->tx_bufs_dma0); > } > > -static void device_init_rd0_ring(struct vnt_private *priv) > +static int device_init_rd0_ring(struct vnt_private *priv) > { > int i; > dma_addr_t curr = priv->rd0_pool_dma; > struct vnt_rx_desc *desc; > + int ret = 0; Don't initialize "ret". When you do that it disables static analysis to find uninitialized variable warnings. > > /* Init the RD0 ring entries */ > for (i = 0; i < priv->opts.rx_descs0; > i ++, curr += sizeof(struct vnt_rx_desc)) { > desc = &priv->aRD0Ring[i]; > desc->rd_info = kzalloc(sizeof(*desc->rd_info), GFP_KERNEL); > - > + if (!desc->rd_info) { > + ret = -ENOMEM; > + goto error; > + } > if (!device_alloc_rx_buf(priv, desc)) > dev_err(&priv->pcid->dev, "can not alloc rx bufs\n"); > We need to handle the case where device_alloc_rx_buf() fails as well... Some years back, I wrote a post about error handling that might be helpful: https://plus.google.com/106378716002406849458/posts/dnanfhQ4mHQ You are using "one err" and "do nothing" style error handling which are described in the post. > @@ -550,20 +554,29 @@ static void device_init_rd0_ring(struct vnt_private *priv) > if (i > 0) > priv->aRD0Ring[i-1].next_desc = cpu_to_le32(priv->rd0_pool_dma); > priv->pCurrRD[0] = &priv->aRD0Ring[0]; > + > + return 0; > +error: > + device_free_rd0_ring(priv); > + return ret; > } Of course, Jia-Ju Bai is correct to say that this is a layering violation. Each function should only clean up after its self. Also, this is a very typical "one err" style bug which I explain about in my g+ post. The rule that applies here is that you should only free things which have been allocated. Since we only partially allocated the rd0 ring, device_free_rd0_ring() will crash when we do: dma_unmap_single(&priv->pcid->dev, rd_info->skb_dma, priv->rx_buf_sz, DMA_FROM_DEVICE); "rd_info" is NULL so rd_info->skb_dma is a NULL dereference. regards, dan carpenter _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel