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AJvYcCXFFJZHGA0/7uD8vkeR1bcxik26JdIlbvu3x13XLecS1Go8+D1z9+doO+UqONN/oC0Jaa7iezY=@vger.kernel.org X-Gm-Message-State: AOJu0YwSfm8FrATaFMHb4hXkP4l1rV7cfZkt1ibLl3uk0S33KEipaYzl QqGr7B5hObF9c+6IGE6efameqKuLIJTcnLm0O4ADTXqEuGy/XvBQLdSiRqDmH6lxiAtbFm4/bIA ySeO7epELF4zgCDjTsTfM2dZkJjGZR0nerI66+tRTjqvj8BKwivLctCoXYs8= X-Google-Smtp-Source: AGHT+IGDVML1NYMfVqSYdhcdpc9xcQHWjloVEML4QXkiG+02PaSmZ13z3yTBKFuOzRP6MTtYDWTV8MJC6Ld9zv0JxfzazQFo08r6 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:62a:b0:659:9a49:9069 with SMTP id 006d021491bc7-6599a95e8c6mr3041769eaf.52.1765200146611; Mon, 08 Dec 2025 05:22:26 -0800 (PST) Date: Mon, 08 Dec 2025 05:22:26 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6936d112.a70a0220.38f243.00a7.GAE@google.com> Subject: [syzbot] [net?] possible deadlock in ipv6_sock_mc_close (4) From: syzbot To: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, horms@kernel.org, kuba@kernel.org, kuniyu@google.com, linux-kernel@vger.kernel.org, lucien.xin@gmail.com, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 8f7aa3d3c732 Merge tag 'net-next-6.19' of git://git.kernel.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=1564201a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=9e5198eaf003f1d1 dashboard link: https://syzkaller.appspot.com/bug?extid=c59e6bb54e7620495725 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17a53192580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13f3301a580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/5fe312c4cf90/disk-8f7aa3d3.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/c7a1f54ef730/vmlinux-8f7aa3d3.xz kernel image: https://storage.googleapis.com/syzbot-assets/64a3779458bb/bzImage-8f7aa3d3.xz The issue was bisected to: commit b7ddb55f31279f4e59acde3395fc03c3d94b6e5f Author: Kuniyuki Iwashima Date: Thu Oct 23 23:16:56 2025 +0000 sctp: Use sctp_clone_sock() in sctp_do_peeloff(). bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=105db01a580000 final oops: https://syzkaller.appspot.com/x/report.txt?x=125db01a580000 console output: https://syzkaller.appspot.com/x/log.txt?x=145db01a580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c59e6bb54e7620495725@syzkaller.appspotmail.com Fixes: b7ddb55f3127 ("sctp: Use sctp_clone_sock() in sctp_do_peeloff().") ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.17/5997 is trying to acquire lock: ffff88803021dee0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1700 [inline] ffff88803021dee0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: ipv6_sock_mc_close+0xd3/0x140 net/ipv6/mcast.c:348 but task is already holding lock: ffff88803021d5a0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1700 [inline] ffff88803021d5a0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_getsockopt+0x135/0xb60 net/sctp/socket.c:8131 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sk_lock-AF_INET6); lock(sk_lock-AF_INET6); *** DEADLOCK *** May be due to missing lock nesting notation 1 lock held by syz.0.17/5997: #0: ffff88803021d5a0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1700 [inline] #0: ffff88803021d5a0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_getsockopt+0x135/0xb60 net/sctp/socket.c:8131 stack backtrace: CPU: 1 UID: 0 PID: 5997 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x2540/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 lock_sock_nested+0x48/0x100 net/core/sock.c:3780 lock_sock include/net/sock.h:1700 [inline] ipv6_sock_mc_close+0xd3/0x140 net/ipv6/mcast.c:348 inet6_release+0x47/0x70 net/ipv6/af_inet6.c:482 __sock_release net/socket.c:653 [inline] sock_release+0x85/0x150 net/socket.c:681 sctp_getsockopt_peeloff_common+0x56b/0x770 net/sctp/socket.c:5732 sctp_getsockopt_peeloff_flags+0x13b/0x230 net/sctp/socket.c:5801 sctp_getsockopt+0x3ab/0xb60 net/sctp/socket.c:8151 do_sock_getsockopt+0x2b4/0x3d0 net/socket.c:2399 __sys_getsockopt net/socket.c:2428 [inline] __do_sys_getsockopt net/socket.c:2435 [inline] __se_sys_getsockopt net/socket.c:2432 [inline] __x64_sys_getsockopt+0x1a5/0x250 net/socket.c:2432 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8a4018f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc8290fbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 00007f8a403e5fa0 RCX: 00007f8a4018f749 RDX: 000000000000007a RSI: 0000000000000084 RDI: 0000000000000003 RBP: 00007f8a40213f91 R08: 0000200000000040 R09: 0000000000000000 R10: 0000200000000340 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8a403e5fa0 R14: 00007f8a403e5fa0 R15: 0000000000000005 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup