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Fri, 8 May 2026 16:38:44 +0000 (GMT) Received: from t83lp71.lnxne.boe (unknown [9.87.84.240]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 8 May 2026 16:38:44 +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/iucv: fix UAF in afiucv_netdev_event() Date: Fri, 8 May 2026 18:38:36 +0200 Message-ID: <20260508163836.2207648-1-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-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA4MDE2NiBTYWx0ZWRfX6ne6nNcUN7hI DGA3JPcn754O6DPoQp3kwCUwybpTF08uGQnG5JUpUIZsS9QZUt7xMdxAhYz0zsSNPIxb06yKpPg QXiugF4VQ/aQwmC3oS3jVFKHynAwEamNhRmJHwWbx1wB1qVoJKbRWPZE4ScgJ4FrOBIPBRQ7/M1 LswjUaTbSif8LRpFH9n5c9+ksuZCKDOm57DPjOPsDgq4+qzu0mmuZ2JvNSzW3NQGTsvoE/kBatZ UnN0GOwPDFfSQ4jz05tehNOnB0bf+KCTtP5P0jch6EESX9F8p/1welR/ZAQcTOH+JbUhnNh+U4t bE9MMNuMhkj8SUmq00l94U9Q/L+Rs7Tlm+c66tZexEvAdUeCc0IRPgfstnb++i5BYZ/p6/K1xKF s1enopHUDmNJL685LtnVAZvhE0oPd5K+tGzKY6SIBOMyXHsq97QoB1Y4fa2zkKjQh6VkuFEE5Ew lyFQq7GPRBpjdWRjlpg== X-Proofpoint-ORIG-GUID: JEVlk-_3wMEdY9IuZUt8xkW4xhBih6Mg X-Proofpoint-GUID: JEVlk-_3wMEdY9IuZUt8xkW4xhBih6Mg X-Authority-Analysis: v=2.4 cv=ctWrVV4i c=1 sm=1 tr=0 ts=69fe119a cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=2L6bTA5ms6rrk1lURLYA:9 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 priorityscore=1501 lowpriorityscore=0 adultscore=0 clxscore=1011 suspectscore=0 impostorscore=0 spamscore=0 malwarescore=0 phishscore=0 bulkscore=0 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 --- 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