From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f80.google.com (mail-oa1-f80.google.com [209.85.160.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E7A729BD91 for ; Tue, 21 Apr 2026 15:34:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776785665; cv=none; b=GObMDBYiDV+5EJJCRdkeGe7XM+n7J+K4hQ0isqDsgsV1SzXQR5mhbe4Qyx7up4VM4xxwTtorlCqj1ImxRs4Q30KCE24bYRKrSWR3j5xD7eC0DwMX2V0rA2eaoVsU/JbPa3Osv9lItbOlR1Vle7amXyh8H2HpsycJJ9zJVeYqcv4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776785665; c=relaxed/simple; bh=rZArWJHmRxt1om2wMFT5MbRr454f6XOP0FkgvXszVdc=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=FcnBkQVZz8aG2uv3JTyzvLpSy06jORsO7SWblvW/F1gCcvC3dYdeI/Bod9fa7FHjrGSpYozQpuAjlNCqrotMsz2ItGe6Nd34/IBPZCuxUZr0o3GtlsLcNkUFm8c+tjFLnOLVgXl3qfDXPKkad9zCFp/B8IYBmd9IEwhz+erDFY8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.160.80 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oa1-f80.google.com with SMTP id 586e51a60fabf-42c06895be6so3599337fac.0 for ; Tue, 21 Apr 2026 08:34:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776785662; x=1777390462; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=wy8SfbKEgZbWh8Ix/2J0vDXqxb5Y/5n9Sl1yQnlcfBM=; b=NgQJJakc7z1aYofiK4AXwuaxtRhi6TnYtu4gSaU+yQKHlczW8SL0w62+iszQI3aUE/ lMCDz85rzfcBYR6+DC/Cbcaej39do2wKUeAFBDjGnFt5nbMvtSpy2ikyemBIC878Jwu/ tgO3454v0Rt/WulqxiQp09CKETm1fX6PmABmgwoKu/3qP6MY52iiogrPR63mC0t5ql7A UCTPOQuQWv2pSFbydnTmzP9vdBb/AfQz8J9/kxKEH2zSdIMpKA8X7e6Q2AvNYoujM5WR SrAUObsN0mNcdNluFBzz1Nd82W0YuRcpL8mRYiFLKN7h11/1WhDIiKPTRv0ioPJO29ul bGPw== X-Forwarded-Encrypted: i=1; AFNElJ8b/6IaY6AveLbHZ76URX2som1lUW3qnwXSmr0VGMLnI0eaIVtVhMrGAj69XqrNr09K/AyXf1Q=@vger.kernel.org X-Gm-Message-State: AOJu0YwEEkk2T5LdM9DwEanUKiS4aF5Zda/BD6IMLrcaLFs1SHDI0kk8 +lYnUE7o3lJHmnwM5Q5oebpUyKWVcvAr+bx0OEfdP9w9GOZyILMekg8tgwdntCUlpPM7Lk/+h37 eiehyN0imJA6xW+5VFSr/TxxO9Zgy2rWY+KdkfWc6RzdOTHr5uNILqbKUMxM= 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:c90:b0:688:6d55:195 with SMTP id 006d021491bc7-69462f2f14fmr10770363eaf.57.1776785662586; Tue, 21 Apr 2026 08:34:22 -0700 (PDT) Date: Tue, 21 Apr 2026 08:34:22 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69e798fe.050a0220.24bfd3.0033.GAE@google.com> Subject: [syzbot] [sctp?] WARNING: refcount bug in sctp_association_hold From: syzbot To: davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-sctp@vger.kernel.org, lucien.xin@gmail.com, marcelo.leitner@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: c1f49dea2b8f Merge tag 'mm-hotfixes-stable-2026-04-19-00-1.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15de0e6a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=507c1c0a12a79510 dashboard link: https://syzkaller.appspot.com/bug?extid=61bdf856ff699245c643 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-c1f49dea.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/98ce9fed1a97/vmlinux-c1f49dea.xz kernel image: https://storage.googleapis.com/syzbot-assets/b02e163ec959/bzImage-c1f49dea.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+61bdf856ff699245c643@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x111/0x130 lib/refcount.c:25, CPU#0: swapper/0/0 Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:refcount_warn_saturate+0x111/0x130 lib/refcount.c:25 Code: 06 e8 e3 e8 11 fd 48 8d 3d 8c d6 ef 0b 67 48 0f b9 3a e8 d2 e8 11 fd 5b 5d c3 cc cc cc cc e8 c6 e8 11 fd 48 8d 3d 7f d6 ef 0b <67> 48 0f b9 3a e8 b5 e8 11 fd 5b 5d e9 0e de a2 06 48 89 df e8 a6 RSP: 0000:ffffc90000007bd8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888075d2e004 RCX: ffffffff84f6dc0b RDX: ffffffff8e4955c0 RSI: ffffffff84f6dcba RDI: ffffffff90e6b340 RBP: 0000000000000002 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000002 R11: 0000000000000000 R12: ffff888075d2e004 R13: 0000000000000002 R14: ffff88804fd3cbd0 R15: ffff888050620000 FS: 0000000000000000(0000) GS:ffff8880970ee000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000080066018 CR3: 000000004c3cc000 CR4: 0000000000352ef0 Call Trace: __refcount_add include/linux/refcount.h:289 [inline] __refcount_inc include/linux/refcount.h:366 [inline] refcount_inc include/linux/refcount.h:383 [inline] sctp_association_hold+0x9f/0xb0 net/sctp/associola.c:843 sctp_generate_timeout_event+0x292/0x3f0 net/sctp/sm_sideeffect.c:284 call_timer_fn+0x19a/0x640 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers+0x75f/0xaf0 kernel/time/timer.c:2374 __run_timer_base kernel/time/timer.c:2386 [inline] __run_timer_base kernel/time/timer.c:2378 [inline] run_timer_base+0x114/0x190 kernel/time/timer.c:2395 run_timer_softirq+0x1a/0x50 kernel/time/timer.c:2405 handle_softirqs+0x1ea/0xa00 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:steal_cookie_task kernel/sched/core.c:6401 [inline] RIP: 0010:sched_core_balance+0x3fd/0xea0 kernel/sched/core.c:6422 Code: 7e 48 48 89 4c 24 40 e8 61 df c2 09 48 8b 4c 24 40 e9 3a 01 00 00 49 8d 7f 48 e8 4e df c2 09 e8 79 76 3a 00 fb 80 7c 24 30 00 <0f> 85 92 00 00 00 8d 4d 01 48 63 d1 49 39 d4 73 48 83 f9 08 74 41 RSP: 0000:ffffffff8e407b80 EFLAGS: 00000246 RAX: 000000000046d04f RBX: ffff88802b23b3c8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8df51613 RDI: ffffffff8c1c0200 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001 R13: dffffc0000000000 R14: ffff88802b33b380 R15: ffff88802b23b380 do_balance_callbacks kernel/sched/core.c:5017 [inline] __balance_callbacks+0x21d/0x6e0 kernel/sched/core.c:5073 __schedule+0x31b9/0x6820 kernel/sched/core.c:7191 schedule_idle+0x54/0x80 kernel/sched/core.c:7308 do_idle+0x2dd/0x590 kernel/sched/idle.c:381 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451 rest_init+0x251/0x260 init/main.c:762 start_kernel+0x484/0x490 init/main.c:1220 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x148 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: e8 e3 e8 11 fd call 0xfd11e8e8 5: 48 8d 3d 8c d6 ef 0b lea 0xbefd68c(%rip),%rdi # 0xbefd698 c: 67 48 0f b9 3a ud1 (%edx),%rdi 11: e8 d2 e8 11 fd call 0xfd11e8e8 16: 5b pop %rbx 17: 5d pop %rbp 18: c3 ret 19: cc int3 1a: cc int3 1b: cc int3 1c: cc int3 1d: e8 c6 e8 11 fd call 0xfd11e8e8 22: 48 8d 3d 7f d6 ef 0b lea 0xbefd67f(%rip),%rdi # 0xbefd6a8 * 29: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2e: e8 b5 e8 11 fd call 0xfd11e8e8 33: 5b pop %rbx 34: 5d pop %rbp 35: e9 0e de a2 06 jmp 0x6a2de48 3a: 48 89 df mov %rbx,%rdi 3d: e8 .byte 0xe8 3e: a6 cmpsb %es:(%rdi),%ds:(%rsi) --- 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. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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