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Fri, 8 May 2026 17:05:36 +0000 (GMT) Received: from t83lp71.lnxne.boe (unknown [9.87.84.240]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 8 May 2026 17:05:36 +0000 (GMT) From: Nagamani PV To: wintera@linux.ibm.com, aswin@linux.ibm.com, sidraya@linux.ibm.com, hidayath@linux.ibm.com, pasic@linux.ibm.com, mjambigi@linux.ibm.com, dk@linux.ibm.com, twinkler@linux.ibm.com, jaka@linux.ibm.com, wenjia@linux.ibm.com, gbayer@linux.ibm.com, linux390-list@tuxmaker.boeblingen.de.ibm.com Cc: Nagamani PV , stable@vger.kernel.org, syzbotz+89435e7383b82238dd91@linux.ibm.com Subject: [PATCH net-next V2] net/iucv: fix UAF in afiucv_netdev_event() Date: Fri, 8 May 2026 19:05:34 +0200 Message-ID: <20260508170534.2208812-1-nagamani@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=XPQAjwhE c=1 sm=1 tr=0 ts=69fe17e7 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=2L6bTA5ms6rrk1lURLYA:9 X-Proofpoint-ORIG-GUID: CDxbwSiDIwL0iItnFBCVRzaDxvcO5JeC X-Proofpoint-GUID: CDxbwSiDIwL0iItnFBCVRzaDxvcO5JeC X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA4MDE2NiBTYWx0ZWRfX+JXJp4wjkQp2 zhEIy4ilSI3/Rf1FS75ZN9PdHkXdrsLoGA2s3M1wMtRydQmvtixzNxl41sdTl2V3CMnLR6IM5WQ yj6JibEq1bi1segWsJ2z30xtBeBhi6y0mZglJ6GPc21p4IcpxCJi9CCj2kJBpETpyTlIaOWZnZ8 RI75kiQ/cCsfdENCogWZ4vTXbmaQy9xjW1tMYKpYW04eTjZGqiBOJKXtIwTqqfzOwl/8pjA9D0T dtzbEP+dJXyRgGQODzM9eCLp4eEmRg5VuOVIkeJAfzKawYpLNUgkrBEXxUEuxFzjP65L2V+C2YK 1pWhig3TazoPJP0m6rXYK+kI/W435Ibf4NvexzqZe5Sx2aPtl6g0lGGCTaUd0lv9b2+b0SRj4U1 648XM94SpS/vVWhYf4ymIcKx6709kq06arWHosn0ikH70V6IfrhPNq+z9/3XMmrQGULzKensd+G gW/4uPyFJD9careV5gA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-07_02,2026-05-08_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 spamscore=0 priorityscore=1501 impostorscore=0 phishscore=0 malwarescore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605080166 afiucv_netdev_event() traverses iucv_sk_list without holding iucv_sk_list.lock. A concurrent socket teardown can unlink and free the socket via iucv_sock_kill() while the notifier path is still iterating over the list, leading to a possible use-after-free when dereferencing the socket. Protect the traversal using the existing read-side lock, matching the locking pattern already used by other iucv_sk_list traversal paths in af_iucv.c. Use read_lock()/read_unlock() to remain consistent with existing softirq/tasklet-side readers in the same file. Fixes: 9fbd87d41392 ("af_iucv: handle netdev events") Cc: stable@vger.kernel.org Reported-by: syzbotz+89435e7383b82238dd91@linux.ibm.com Closes: https://lnxgwne1.boeblingen.de.ibm.com/linux-ci/syzbot/dashboard/bug?extid=89435e7383b82238dd91 Suggested-by: Hidayath Khan Signed-off-by: Nagamani PV --- v2: - Target net-next (missed in v1 subject) --- net/iucv/af_iucv.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index 72dfccd4e3d5..e8a0b55fc55d 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -2188,6 +2188,7 @@ static int afiucv_netdev_event(struct notifier_block *this, switch (event) { case NETDEV_REBOOT: case NETDEV_GOING_DOWN: + read_lock(&iucv_sk_list.lock); sk_for_each(sk, &iucv_sk_list.head) { iucv = iucv_sk(sk); if ((iucv->hs_dev == event_dev) && @@ -2198,6 +2199,7 @@ static int afiucv_netdev_event(struct notifier_block *this, sk->sk_state_change(sk); } } + read_unlock(&iucv_sk_list.lock); break; case NETDEV_DOWN: case NETDEV_UNREGISTER: -- 2.53.0