From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 927782E093A; Mon, 20 Apr 2026 16:05:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776701113; cv=none; b=Zdiqkum662g0FHi6HI+Suw28YN6ue8XlW022CS0UI1aNzAQ96h609kI7lAe/WvikoYpfJSSj5jGVyPr45s0hf1B5Ih83A3yYCdgmCUKkit96lS0G5SRTysM0E/wCNFaeC7OS8Dp183SKwTD7Ep7cOZbjCNdNe4SIcwRcpPVdmJs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776701113; c=relaxed/simple; bh=dMIeDf4UTbjBx9P4BhnI/cc7eG2PMapWz4S5mQZ1aY8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Mpr44MQ3pG/xTzLwz+cLVl/SVmREEo04uVclGbykiMKHl/D7+5W+TggyuMVWG7APAjVxj0PmUeAUE/6gGNuJdv7ZWYmIb7Wc2qFUDt5wRKD2F8HwFFhfwUvaZM9dj650ORoNN6BfApEoXD9uIsqSqe02A35+PUZuxgwYK+a7Gaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fdd0Ih3b; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fdd0Ih3b" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2ABAFC19425; Mon, 20 Apr 2026 16:05:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776701113; bh=dMIeDf4UTbjBx9P4BhnI/cc7eG2PMapWz4S5mQZ1aY8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fdd0Ih3bRr2lKF0pCMENEvkeZVaPlea4F3jGIhmhmGpEe8u3NYOjDPQ94wEmn+IAd +A2qn5r/34GQfarcMdOLweZqyv0WaMcT7sImCcZxr8nxIyn80cZoKlztUqrJOrJv7t 1BgcFaShxUurzMS0Uak/lztXHFLvtHgTQH55Wgjw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+c025d34b8eaa54c571b8@syzkaller.appspotmail.com, Abhishek Kumar , Hans Verkuil Subject: [PATCH 6.18 187/198] media: em28xx: fix use-after-free in em28xx_v4l2_open() Date: Mon, 20 Apr 2026 17:42:46 +0200 Message-ID: <20260420153942.351603845@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153935.605963767@linuxfoundation.org> References: <20260420153935.605963767@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Abhishek Kumar commit a66485a934c7187ae8e36517d40615fa2e961cff upstream. em28xx_v4l2_open() reads dev->v4l2 without holding dev->lock, creating a race with em28xx_v4l2_init()'s error path and em28xx_v4l2_fini(), both of which free the em28xx_v4l2 struct and set dev->v4l2 to NULL under dev->lock. This race leads to two issues: - use-after-free in v4l2_fh_init() when accessing vdev->ctrl_handler, since the video_device is embedded in the freed em28xx_v4l2 struct. - NULL pointer dereference in em28xx_resolution_set() when accessing v4l2->norm, since dev->v4l2 has been set to NULL. Fix this by moving the mutex_lock() before the dev->v4l2 read and adding a NULL check for dev->v4l2 under the lock. Reported-by: syzbot+c025d34b8eaa54c571b8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c025d34b8eaa54c571b8 Fixes: 8139a4d583ab ("[media] em28xx: move v4l2 user counting fields from struct em28xx to struct v4l2") Cc: stable@vger.kernel.org Signed-off-by: Abhishek Kumar Signed-off-by: Hans Verkuil Signed-off-by: Greg Kroah-Hartman --- drivers/media/usb/em28xx/em28xx-video.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) --- a/drivers/media/usb/em28xx/em28xx-video.c +++ b/drivers/media/usb/em28xx/em28xx-video.c @@ -2126,7 +2126,7 @@ static int em28xx_v4l2_open(struct file { struct video_device *vdev = video_devdata(filp); struct em28xx *dev = video_drvdata(filp); - struct em28xx_v4l2 *v4l2 = dev->v4l2; + struct em28xx_v4l2 *v4l2; enum v4l2_buf_type fh_type = 0; int ret; @@ -2143,13 +2143,19 @@ static int em28xx_v4l2_open(struct file return -EINVAL; } + if (mutex_lock_interruptible(&dev->lock)) + return -ERESTARTSYS; + + v4l2 = dev->v4l2; + if (!v4l2) { + mutex_unlock(&dev->lock); + return -ENODEV; + } + em28xx_videodbg("open dev=%s type=%s users=%d\n", video_device_node_name(vdev), v4l2_type_names[fh_type], v4l2->users); - if (mutex_lock_interruptible(&dev->lock)) - return -ERESTARTSYS; - ret = v4l2_fh_open(filp); if (ret) { dev_err(&dev->intf->dev,