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Tue, 3 Nov 2020 12:03:15 +0000 Subject: Re: [PATCH 2/2] vfio/fsl-mc: prevent underflow in vfio_fsl_mc_mmap() To: Dan Carpenter Cc: Alex Williamson , Cornelia Huck , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org References: <20201023112947.GF282278@mwanda> From: Diana Craciun OSS Message-ID: Date: Tue, 3 Nov 2020 14:03:08 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:83.0) Gecko/20100101 Thunderbird/83.0 In-Reply-To: <20201023112947.GF282278@mwanda> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [86.121.79.46] X-ClientProxiedBy: AM0PR08CA0024.eurprd08.prod.outlook.com (2603:10a6:208:d2::37) To VI1PR0402MB2815.eurprd04.prod.outlook.com (2603:10a6:800:ae::16) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.1.122] (86.121.79.46) by AM0PR08CA0024.eurprd08.prod.outlook.com (2603:10a6:208:d2::37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: oss.nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 40023dd4-8d26-47a4-61c0-08d87ff071a0 X-MS-Exchange-CrossTenant-AuthSource: VI1PR0402MB2815.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Nov 2020 12:03:15.0189 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: IeivYJoikbRKNnzr+SsQ6rgyLjcPaWerJKdmlkjS1DhvbOLyRqnreayjB/hUPI1H/lw7ALKdMErPO198Y0+23w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0402MB2814 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Acked-by: Diana Craciun On 10/23/2020 2:29 PM, Dan Carpenter wrote: > My static analsysis tool complains that the "index" can be negative. > There are some checks in do_mmap() which try to prevent underflows but > I don't know if they are sufficient for this situation. Either way, > making "index" unsigned is harmless so let's do it just to be safe. > > Fixes: 67247289688d ("vfio/fsl-mc: Allow userspace to MMAP fsl-mc device MMIO regions") > Signed-off-by: Dan Carpenter > --- > drivers/vfio/fsl-mc/vfio_fsl_mc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c > index 21f22e3da11f..f27e25112c40 100644 > --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c > +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c > @@ -472,7 +472,7 @@ static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct *vma) > { > struct vfio_fsl_mc_device *vdev = device_data; > struct fsl_mc_device *mc_dev = vdev->mc_dev; > - int index; > + unsigned int index; > > index = vma->vm_pgoff >> (VFIO_FSL_MC_OFFSET_SHIFT - PAGE_SHIFT); > >