From patchwork Fri Jan 24 14:13:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Carpenter X-Patchwork-Id: 11350337 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9D9156C1 for ; Fri, 24 Jan 2020 14:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7ADD82087E for ; Fri, 24 Jan 2020 14:14:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="IgnQooUn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390182AbgAXOOi (ORCPT ); Fri, 24 Jan 2020 09:14:38 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:56120 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387508AbgAXOOi (ORCPT ); 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Fri, 24 Jan 2020 14:14:17 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 2xqmwfbve8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 24 Jan 2020 14:14:16 +0000 Received: from abhmp0006.oracle.com (abhmp0006.oracle.com [141.146.116.12]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 00OEE8s5001970; Fri, 24 Jan 2020 14:14:08 GMT Received: from kili.mountain (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 24 Jan 2020 06:14:07 -0800 Date: Fri, 24 Jan 2020 17:13:56 +0300 From: Dan Carpenter To: Hans Verkuil , syzbot , Hillf Danton Cc: Alan Stern , Allison Randal , Greg Kroah-Hartman , Souptick Joarder , andreyknvl@google.com, bnvandana@gmail.com, laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-usb@vger.kernel.org, mchehab@kernel.org, syzkaller-bugs@googlegroups.com Subject: [PATCH] media: usbvision: Fix a use after free in v4l2_release() Message-ID: <20200124141356.365bgzg2lp3tjedm@kili.mountain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200123102707.2596-1-hdanton@sina.com> X-Mailer: git-send-email haha only kidding User-Agent: NeoMutt/20170113 (1.7.2) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9509 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001240118 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9509 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001240119 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Syzbot triggered a use after free in v5.5-rc6: BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459 Allocated by task 94: usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline] usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469 Freed by task 1913: kfree+0xd5/0x300 mm/slub.c:3957 usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364 usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130 v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455 The problem is that the v4l2_release() calls usbvision_release() which frees "usbvision" but v4l2_release() still wants to use "usbvision->vdev". One solution is to make this devm_ allocated memory so the memory isn't freed until later. Reported-by: syzbot+75287f75e2fedd69d680@syzkaller.appspotmail.com Signed-off-by: Dan Carpenter --- I copied this idea from a different driver, but I haven't tested it. I wanted to try the #syz fix command to see if it works. drivers/media/usb/usbvision/usbvision-video.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/media/usb/usbvision/usbvision-video.c b/drivers/media/usb/usbvision/usbvision-video.c index 93d36aab824f..07b4763062c4 100644 --- a/drivers/media/usb/usbvision/usbvision-video.c +++ b/drivers/media/usb/usbvision/usbvision-video.c @@ -1312,7 +1312,7 @@ static struct usb_usbvision *usbvision_alloc(struct usb_device *dev, { struct usb_usbvision *usbvision; - usbvision = kzalloc(sizeof(*usbvision), GFP_KERNEL); + usbvision = devm_kzalloc(&dev->dev, sizeof(*usbvision), GFP_KERNEL); if (!usbvision) return NULL; @@ -1336,7 +1336,6 @@ static struct usb_usbvision *usbvision_alloc(struct usb_device *dev, v4l2_ctrl_handler_free(&usbvision->hdl); v4l2_device_unregister(&usbvision->v4l2_dev); err_free: - kfree(usbvision); return NULL; } @@ -1361,7 +1360,6 @@ static void usbvision_release(struct usb_usbvision *usbvision) v4l2_ctrl_handler_free(&usbvision->hdl); v4l2_device_unregister(&usbvision->v4l2_dev); - kfree(usbvision); PDEBUG(DBG_PROBE, "success"); }