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Wed, 17 Dec 2025 09:39:11 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5CF862004B; Wed, 17 Dec 2025 09:39:11 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 062AB20040; Wed, 17 Dec 2025 09:39:11 +0000 (GMT) Received: from [9.52.217.163] (unknown [9.52.217.163]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 17 Dec 2025 09:39:10 +0000 (GMT) Message-ID: <03a57f0d-2b09-47d4-b1ac-f86dc128356b@linux.ibm.com> Date: Wed, 17 Dec 2025 10:39:10 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Alexandra Winter Subject: Re: [syzbot] [smc?] general protection fault in smc_diag_dump_proto To: syzbot , agordeev@linux.ibm.com, aha310510@gmail.com, alibuda@linux.alibaba.com, davem@davemloft.net, dust.li@linux.alibaba.com, edumazet@google.com, gbayer@linux.ibm.com, guwen@linux.alibaba.com, horms@kernel.org, jaka@linux.ibm.com, julianr@linux.ibm.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, lizhi.xu@windriver.com, netdev@vger.kernel.org, pabeni@redhat.com, sidraya@linux.ibm.com, syzkaller-bugs@googlegroups.com, tonylu@linux.alibaba.com, wenjia@linux.ibm.com References: <6935028e.a70a0220.38f243.0041.GAE@google.com> Content-Language: en-US In-Reply-To: <6935028e.a70a0220.38f243.0041.GAE@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Ds05PRbPaWBorWsEA3kLnsPCRBwfP2Rx X-Proofpoint-ORIG-GUID: WPsxbPA1b4TKEMZDsEZF1cA4MOQllvhN X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjEzMDAyMyBTYWx0ZWRfX/UYwe2kh6Oox RB7owxuW/UOYRDqBly7lMkzcQck9l4xPTlTCsbPJYX5kC0pliKyTr+AoaO+5aaXSKo6yTSoT9pL J09T9c8pqiVRTUAqehH6DxlB3+lkzGOP7byYJhBGYj7q3bb7mV0cxJtwaemjoTUg3HpHriGBDRj LkliBgH95vX3omRHQbBUOLa8zb8T5kDKfsG3lzm4Zwz3eUitLum3fnzslCxXUKS2EHzhXWYP4vU xtgVKlfY97RCyeYyImGOKW7bdwUSGgAgJQbNIhZkAEdAxjMvFhLu0SOJ2iGN4QeXa+oYZ6KRV5c eI5WgCm5kxor8Y7cQLiVD9oZRrLXhBsO0EcFDO0vUy2FKwzayuIzEqJG92fQArFHjl+vE2guyFD D6sAkk4XgKhCEMmiPEVhgc/SJva8Dg== X-Authority-Analysis: v=2.4 cv=L/MQguT8 c=1 sm=1 tr=0 ts=69427a44 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=wP3pNCr1ah4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=edf1wS77AAAA:8 a=oHvirCaBAAAA:8 a=VnNF1IyMAAAA:8 a=KtLUjaqJyylS1UVrumcA:9 a=QEXdDO2ut3YA:10 a=DcSpbTIhAlouE1Uv7lRv:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-17_01,2025-12-16_05,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 malwarescore=0 adultscore=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 bulkscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2512130023 On 07.12.25 05:29, syzbot wrote: > syzbot suspects this issue was fixed by commit: > > commit d324a2ca3f8efd57f5839aa2690554a5cbb3586f > Author: Alexandra Winter > Date: Thu Sep 18 11:04:50 2025 +0000 > > dibs: Register smc as dibs_client > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16d64eb4580000 > start commit: dbb9a7ef3478 net: fjes: use ethtool string helpers > git tree: net-next > kernel config: https://syzkaller.appspot.com/x/.config?x=a9d1c42858837b59 > dashboard link: https://syzkaller.appspot.com/bug?extid=f69bfae0a4eb29976e44 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=178f0d5f980000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10906b40580000 > > If the result looks correct, please mark the issue as fixed by replying with: > > #syz fix: dibs: Register smc as dibs_client > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection Unfortunately, I don't think d324a2ca3f8e ("dibs: Register smc as dibs_client") has fixed this issue. Iiuc https://syzkaller.appspot.com/bug?extid=f69bfae0a4eb29976e44 shows an occurrence on 2025/10/17 13:18 net-next 7e0d4c111369 that code level already contains the bisected commit 7e0d4c111369. Looking at net/smc/af_smc.c:smc_init() I think the bisected patch has changed the timing of smc_ism_init() which may have led to the bisect result. I think the issue may stem from the order of calls in smc_init(). Especially smc_nl_init(), proto_register(&smc_proto, 1), proto_register(&smc_proto6, 1), sock_register(&smc_sock_family_ops) are all being called before: INIT_HLIST_HEAD(&smc_v4_hashinfo.ht); INIT_HLIST_HEAD(&smc_v6_hashinfo.ht); I think this can lead to the described "KASAN: null-ptr-deref", when calling smc_diag_handler() while the module is still being initialized. I tried to reproduce such a race by calling smc_pnet and 'modprobe -r smc_diag smc'. But I did not hit a KASAN warning with that setting. I'll send a patch nevertheless.