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Thu, 9 Jul 2026 17:17:45 +0000 (GMT) Message-ID: Date: Thu, 9 Jul 2026 19:17:44 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net/iucv: take a reference on the socket found in afiucv_hs_rcv() To: sashiko-reviews@lists.linux.dev, Bryam Vargas Cc: Alexander Gordeev , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, Hidayath Khan References: <20260705-b4-disp-fc79c0dc-v1-1-d2cdcb57afa9@proton.me> <20260707032441.B1FB31F00A3A@smtp.kernel.org> Content-Language: en-US From: Alexandra Winter In-Reply-To: <20260707032441.B1FB31F00A3A@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Q/XiJY2a c=1 sm=1 tr=0 ts=6a4fd7be cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=mpG3tCo3JFPGy_rZ:21 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=mJcjGnY3pr7I_6ufGOQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: VWMUhkT7r8-ws6wl3HKVO9WD32o1xS2R X-Proofpoint-ORIG-GUID: VWMUhkT7r8-ws6wl3HKVO9WD32o1xS2R X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDE2NCBTYWx0ZWRfXyjszKf11lMKo eQWU3FVm5puUEDcLJa1i6VkwlbEQ3ve3cggSxOOk44KmzZtGEkiFwrchyn8nNvXhbOyys37M3F3 ggrV23m9Vbqq5lw37FwKV70h7uNLYu4= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDE2NCBTYWx0ZWRfXwzBTYai0E8U7 9X36QJ39dw6A3Tz5ceD9wBd1Nj83dudkntDfZyTWBUSlGoGy7A2UYXPRqYadCD2r7sHlKWrSiEW S0NKyt4pOiH9SVahZ6W01FDmeaHnjj/Ud9uzBwKWhof+HJhpKx3K3HQPCVMXwKX3rad5mVcGwxh dbDSfqmnZDX3XoOv8gRKFoQVK7TqqvyNG0Z2uDi5izt0TJzE1DNiW0+TA6IPnSUnYi4czdi4QW8 +Laanu62+/xWl1Co94AFxm0CJhhyCFZBEtwccwcbw0mOOC8iIEo6OWbtsEO67EfOQSIXBAO1Lzc X1ubXcAzCBMVhp5Oe6uuVB6a8/+V9j4rhVNukVwv/pNj2GGo7so8H9rgHRF5EimYghPY3WgAqFG Qz2AsbPx5jiNehJb0kEZOonYtJHmV2rEHc2/VYPFXnsOxH256voKqUMAKG71wnNbECV10Dql56C ddSMgGXkVOM8hKXJDRA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_03,2026-07-09_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 bulkscore=0 clxscore=1011 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090164 On 07.07.26 05:24, sashiko-bot@kernel.org wrote: > [Severity: High] > This is a pre-existing issue, but does modifying the socket state from a > softirq context corrupt the socket state machine? > > Since this handler runs in softirq context when network packets arrive, it > acquires the socket spinlock and directly mutates sk->sk_state. > > If a user process is concurrently executing a system call and holds the socket > mutex via lock_sock(), does bypassing the backlog mechanism by failing to check > sock_owned_by_user() cause race conditions? > > [ ... ] > >> @@ -2089,6 +2089,8 @@ static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev, >> } >> } >> } >> + if (sk) >> + sock_hold(sk); >> read_unlock(&iucv_sk_list.lock); >> if (!iucv) >> sk = NULL; >> @@ -2138,6 +2140,8 @@ static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev, >> kfree_skb(skb); >> } >> >> + if (sk) >> + sock_put(sk); >> return err; >> } I think sashiko is right, this patch does not completely close the gap. See my commit message for f558120cd709 ("net/iucv: fix use after free in iucv_sock_close()") Iiuc the socket locking in AF_IUCV is incomplete in general. Bryam, would you like to try to update the socket locking in AF_IUCV altogether? Otherwise Hidayath or I can take that task.