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Wed, 10 Jun 2026 08:30:59 +0000 (GMT) Received: from ALA-EXCHNG02.corp.ad.wrs.com (10.11.224.122) by ALA-EXCHNG02.corp.ad.wrs.com (10.11.224.122) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.61; Wed, 10 Jun 2026 01:30:58 -0700 Received: from pek-yzhou-d3.wrs.com (10.11.232.110) by ALA-EXCHNG02.corp.ad.wrs.com (10.11.224.122) with Microsoft SMTP Server id 15.1.2507.61 via Frontend Transport; Wed, 10 Jun 2026 01:30:56 -0700 From: Yun Zhou To: , , CC: , , Subject: [PATCH v3] media: dvb-core: fix use-after-free in dvb_frontend_open() Date: Wed, 10 Jun 2026 16:30:55 +0800 Message-ID: <20260610083055.3976083-1-yun.zhou@windriver.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Authority-Analysis: v=2.4 cv=NOPlPU6g c=1 sm=1 tr=0 ts=6a2920c3 cx=c_pps a=Lg6ja3A245NiLSnFpY5YKQ==:117 a=Lg6ja3A245NiLSnFpY5YKQ==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=bi6dqmuHe4P4UrxVR6um:22 a=fTW__CHxibyLmBMfj2wP:22 a=edf1wS77AAAA:8 a=hSkVLCK3AAAA:8 a=VwQbUJbxAAAA:8 a=t7CeM3EgAAAA:8 a=XssDyHoSECOwkyI3_iQA:9 a=DcSpbTIhAlouE1Uv7lRv:22 a=cQPPKAXgyycSBL8etih5:22 a=FdTzh2GWekK77mhwV6Dw:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjEwMDA3OSBTYWx0ZWRfXw9eYYVysHRVE fGwMLC1wmd46fPJb+531DbcisLafMoHd0NYYmVLgXYQLvGWfwuUFH/n7KNGp2RdQgz85PQk5fzg 7hfdl8xpLa4XKH0/jfyLBkg97YhCFGIekmVN1JP37Q9f9G+S61Hf6gaszOTBni8AAxG81tW0Dfv k+L+iPYoEw1RJWttWvKJd4WsSk9XdLJ9/64SMlexqvUeX53wfqOzCtra8j/AHwpsrwBNxm6FCcs d+d90WlUce3uMRWSQJxXN+dn0VeWBB7661G12mNIZX93ZSpmpMhSx3OSJ7I+eff20M51BJsSZ3q ZWt6SmLNvYON2RY0QCDhVHNR3s9LBjFrT8aMishrVHlFFlquXk6M+m9vqDInMHRgnbEBx79O1bo rLECqTrma8cZriKK9X9321FxNQfzo41PsWVtiK6/YkzcVuToeHilBVAP9c4QJYr0CpsIDPYox5E s2D6a2r6L5qDTshbJ9A== X-Proofpoint-GUID: 8OQJJzoFlipgMDpZ3iR3mv9AE1w8PVjR X-Proofpoint-ORIG-GUID: 8OQJJzoFlipgMDpZ3iR3mv9AE1w8PVjR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-10_02,2026-06-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 spamscore=0 clxscore=1015 impostorscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606100079 Content-Type: text/plain; charset="utf-8" dvb_frontend_open() calls dvb_generic_release() in its error path after dvb_generic_open() succeeds. dvb_generic_release() drops the device reference via dvb_device_put(), and then dvb_device_open() drops it again in its error handling, causing a use-after-free and refcount underflow. Fix this by incrementing the refcount before dvb_generic_release() in the error path, so that the put inside dvb_generic_release() is balanced and dvb_device_open() remains the sole effective put on open failure. Reported-by: syzbot+40339ea82afa8184ad5d@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D40339ea82afa8184ad5d Cc: stable@vger.kernel.org Fixes: 0fc044b2b5e2 ("media: dvbdev: adopts refcnt to avoid UAF") Signed-off-by: Yun Zhou --- v3: - Simplify fix: increment refcount before dvb_generic_release() instead of introducing __dvb_generic_release() v2: - Fix Fixes tag commit title - Add Closes: link after Reported-by - Cc stable@vger.kernel.org drivers/media/dvb-core/dvb_frontend.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core= /dvb_frontend.c index d082b6c57c76..608525d08277 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -2887,6 +2887,7 @@ static int dvb_frontend_open(struct inode *inode, str= uct file *file) mutex_unlock(&fe->dvb->mdev_lock); err2: #endif + dvb_device_get(dvbdev); dvb_generic_release(inode, file); err1: if (dvbdev->users =3D=3D -1 && fe->ops.ts_bus_ctrl) --=20 2.43.0