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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Ursula Braun , Frank Blaschka Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Stanislav Fomichev References: <20260521-af_iucv_fix2-v1-1-f16b1c510aa9@debian.org> Content-Language: en-US From: Alexandra Winter In-Reply-To: <20260521-af_iucv_fix2-v1-1-f16b1c510aa9@debian.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIyMDEzNiBTYWx0ZWRfXwdjc7oIoHt07 yZuuE7IPCuaYXs424DnLb7Lk2PBLwRUfbiL53/8Ck8axqHWaoFGsmXES+5JsQGbkcUtdHlPvwjU N5188G1ZrBseyzDV6oFLgNFTvTcptD6mauWOf4xJ4+E9aVXVdvkxSN8fQbDXwh1vzgnWvfFUxgC 5Y4dtHX79LephMP/zAmTkt4t48Akn8mQggaI4tYxXK/pKHVatfn7AkC6Q8fwB6WcdAGns8BMzwW wQR16SfPuIBJVfqLRUg6IQF3g13q/oEs0+3YkDXA58TrfsJkMCgAtZahkQ/MuVS0CWi3FnSVEac jjub8D95SuMBXJg/y8L9+0sgj3utvqr79ZKIYP4IGfDuNRvQzzczAopkwBVyVN+37aKe6RTMf7K bnZTMgzVwbg+57SddIJecWWA5IxC/ySvyQSrZp9376NqFX5pFVwPgQYxKo2y4Gasdnx+AUBbdg0 OEMc556q6C5eIs26c5A== X-Proofpoint-GUID: WoJam2dSynZ3Db6YhFov_f44YprzAx86 X-Proofpoint-ORIG-GUID: fIXVeU-yqX4WWdqaqP9MloM6Hz_F2HYe X-Authority-Analysis: v=2.4 cv=aYBRWxot c=1 sm=1 tr=0 ts=6a105bf9 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=pGLkceISAAAA:8 a=xNf9USuDAAAA:8 a=VnNF1IyMAAAA:8 a=IQu2pwtsZk2u-v9NKpYA:9 a=QEXdDO2ut3YA:10 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=2026-05-22_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605220136 On 21.05.26 16:11, Breno Leitao wrote: > Mirror iucv_sock_setsockopt() and wrap the whole switch in > lock_sock()/release_sock(). The pre-existing SO_MSGLIMIT-only lock > becomes redundant and is removed. > > Any AF_IUCV HIPER user can potentially crash the kernel by racing > recvmsg() with getsockopt(SO_MSGSIZE): the SO_MSGSIZE arm dereferences > iucv->hs_dev->mtu after iucv_sock_close() (called from the racing > recvmsg()) has set hs_dev to NULL, producing a NULL pointer dereference > oops. > > Suggested-by: Stanislav Fomichev > Fixes: 51363b8751a6 ("af_iucv: allow retrieval of maximum message size") > Signed-off-by: Breno Leitao > --- > Note1: Not using goto/label to simplify the merge conflict that might > happen with the migration of af_iucv to getsockopt_iter > > Note2: This was only compile-tested. > --- Thank you very much Breno. I ran some regression tests which call IUCV getsockopt(SO_MSGSIZE) while sending and receiving data via IUCV. I have not created a specific reproducer testcase of the described race, which would require enforcing a problem in IUCV over HS congestion management which triggers an error path in recvmsg(). Reviewed-by: Alexandra Winter Tested-by: Alexandra Winter