From nobody Fri Dec 19 14:09:17 2025 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 983D64F5E8 for ; Thu, 21 Dec 2023 09:58:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045176;MF=guanghuifeng@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0VyxGrK9_1703152663; Received: from VM20190228-102.tbsite.net(mailfrom:guanghuifeng@linux.alibaba.com fp:SMTPD_---0VyxGrK9_1703152663) by smtp.aliyun-inc.com; Thu, 21 Dec 2023 17:57:51 +0800 From: Guanghui Feng To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, baolin.wang@linux.alibaba.com, alikernel-developer@linux.alibaba.com Subject: [PATCH v2] uio: Fix use-after-free in uio_open Date: Thu, 21 Dec 2023 17:57:43 +0800 Message-Id: <1703152663-59949-1-git-send-email-guanghuifeng@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1703132808-14322-1-git-send-email-guanghuifeng@linux.alibaba.com> References: <1703132808-14322-1-git-send-email-guanghuifeng@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" core-1 core-2 Reviewed-by: Baolin Wang ------------------------------------------------------- uio_unregister_device uio_open idev =3D idr_find() device_unregister(&idev->dev) put_device(&idev->dev) uio_device_release get_device(&idev->dev) kfree(idev) uio_free_minor(minor) uio_release put_device(&idev->dev) kfree(idev) ------------------------------------------------------- In the core-1 uio_unregister_device(), the device_unregister will kfree idev when the idev->dev kobject ref is 1. But after core-1 device_unregister, put_device and before doing kfree, the core-2 may get_device. Then: 1. After core-1 kfree idev, the core-2 will do use-after-free for idev. 2. When core-2 do uio_release and put_device, the idev will be double freed. To address this issue, we can get idev atomic & inc idev reference with minor_lock. Fixes: 57c5f4df0a5a ("uio: fix crash after the device is unregistered") Signed-off-by: Guanghui Feng Reviewed-by: Baolin Wang --- drivers/uio/uio.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 62082d6..2d572f6 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -466,13 +466,13 @@ static int uio_open(struct inode *inode, struct file = *filep) =20 mutex_lock(&minor_lock); idev =3D idr_find(&uio_idr, iminor(inode)); - mutex_unlock(&minor_lock); if (!idev) { ret =3D -ENODEV; + mutex_unlock(&minor_lock); goto out; } - get_device(&idev->dev); + mutex_unlock(&minor_lock); =20 if (!try_module_get(idev->owner)) { ret =3D -ENODEV; @@ -1064,9 +1064,8 @@ void uio_unregister_device(struct uio_info *info) wake_up_interruptible(&idev->wait); kill_fasync(&idev->async_queue, SIGIO, POLL_HUP); =20 - device_unregister(&idev->dev); - uio_free_minor(minor); + device_unregister(&idev->dev); =20 return; } --=20 1.8.3.1