From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa2-f10.google.com (mail-oa2-f10.google.com [74.125.231.74]) (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 9080734EF04 for ; Tue, 1 Sep 2026 13:58:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788271112; cv=none; b=Kn1cELroQYKHPnEpVnzU5UN5v3VrB4rkbwOrdT3mu4u4VxZZNv++vnFWEG0EnSzk2Z1WuI5ds85nAGPQAIE0gArzzg3Ba7EDmTYWH0iq/cbvpJSa+y8rZT68tNJaetxW4zVCVqru+ZifWDa5EBKYvLrI6BD1RfVJVs7HGlTgXGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788271112; c=relaxed/simple; bh=ENIdvHRw1IiFMIzhFtYNWAzVUTCe7z0d5NvRi0XN0lQ=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=ImXuV55fGhs9X/qdRxscfGwHWkGcT1AizGkJj+aK/PD2oWWZvgxJjDrDOvsbMrMfiIquRVwurE9X1can26gBsjPvm/Rzqp397WjPmXqlC0d8lGhs4zlsOcq3RqQ/zkC9sB/5vfe0toUJzSqtU8wJf95EyXF9nercnEFF5pZNTV8= 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=74.125.231.74 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-oa2-f10.google.com with SMTP id 586e51a60fabf-46abf222dc3so400718fac.0 for ; Tue, 01 Sep 2026 06:58:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788271109; x=1788875909; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=oSScl9b39LFhA6dCrI2VzC9NEUldGRGWmrst0p3B1xs=; b=rCwTFx9z3Mf3RktRUg5ypaGkAAuWNQ/ZELfASARhjrWQSRd5k2RD3lWEHI9mVkhjV7 e06REi89Apni88uqgeM0pWcglLjOhpDK+E1qCIyhLC+C9gCqWm1qb4HQ6mvlBVeGDlc+ 7e+dQ7dsGeuJzmdnMcCBPovUqF1VYscT8RHbEpcpxphgzYBRhlNBphrBlGtxXSzynjBu n3vCsRf2ZIgxb9FED+dYtFuB5JNAK2L483YFahJGKzhMl/pMGq8B+x0CxHn1exU1KeKG 4OE9jf8/MdLSRpt91eznRtE8YTfQ74m2KHi9LfdsHBGKNyX2EwMUj2Ywdk2oS6mFkYZG spRw== X-Forwarded-Encrypted: i=1; AHgh+RortAKdAeEku70Vc+gisaagWmTEP66+x3r7II5TNxHBCqjuJyxypao2nRoWB11iVihKkVU9dNw=@vger.kernel.org X-Gm-Message-State: AFuF++n5cdNlsze0hu03wEWZHh7IDJoy+CvBVnk+gxzrz966/aLne3sQ p4zWG1D/urvZpg0vE90PMx30NiyoSsG4OZsBFK3ZVLG+wYcCJuRo0BjIUL76+X4T86CZD0o2NcE M36JC3Ff1dCOFT1444Z0+rADz81VEwBjwObP8LOPOAUdTBMixMB+tulBYevI= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:60b:b0:6b3:bb82:2736 with SMTP id 006d021491bc7-6b3bb82372amr1185072eaf.17.1788271109452; Tue, 01 Sep 2026 06:58:29 -0700 (PDT) Date: Tue, 01 Sep 2026 06:58:29 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a96da05.08473e0e.15b4ac.0001.GAE@google.com> Subject: [syzbot] [sctp?] WARNING: refcount bug in sctp_generate_timeout_event (4) 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: bf1079577a11 Merge tag 'sched_ext-for-7.3-rc1-fixes' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17d06d9e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=f5baf1a1df3261c2ad8d compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c52dc60311d3/disk-bf107957.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/37591d96a65b/vmlinux-bf107957.xz kernel image: https://storage.googleapis.com/syzbot-assets/729e80af6e39/bzImage-bf107957.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f5baf1a1df3261c2ad8d@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#1: syz.0.2220/13955 Modules linked in: CPU: 1 UID: 0 PID: 13955 Comm: syz.0.2220 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 6b d2 e9 fc 48 8d 3d f4 46 a7 0b 67 48 0f b9 3a eb 4a e8 58 d2 e9 fc 48 8d 3d f1 46 a7 0b <67> 48 0f b9 3a eb 37 e8 45 d2 e9 fc 48 8d 3d ee 46 a7 0b 67 48 0f RSP: 0018:ffffc90000a18c28 EFLAGS: 00010246 RAX: ffffffff84dde548 RBX: 0000000000000002 RCX: ffff88807715be80 RDX: 0000000000000100 RSI: 0000000000000100 RDI: ffffffff90852c40 RBP: 0000000000000000 R08: ffff88807715be80 R09: 0000000000000005 R10: 0000000000000004 R11: 0000000000000100 R12: dffffc0000000000 R13: 0000000000000001 R14: ffff888020fde004 R15: ffff888020fde640 FS: 00007f4a87be06c0(0000) GS:ffff888124dda000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff55dd92eb8 CR3: 000000005800b000 CR4: 0000000000350ef0 Call Trace: sctp_generate_timeout_event+0x1c8/0x390 net/sctp/sm_sideeffect.c:284 call_timer_fn+0x18d/0x5f0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405 handle_softirqs+0x226/0x860 kernel/softirq.c:645 __do_softirq kernel/softirq.c:679 [inline] invoke_softirq kernel/softirq.c:519 [inline] __irq_exit_rcu+0xcb/0x220 kernel/softirq.c:767 irq_exit_rcu+0x9/0x30 kernel/softirq.c:784 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5913 Code: ff ff ff e8 a0 a9 40 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 f2 44 f1 11 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 ba 25 6d ff cc 48 8d 3d 77 31 da RSP: 0018:ffffc9000dabfac8 EFLAGS: 00000282 RAX: b29753db72d85c00 RBX: 0000000000000001 RCX: 8000000000000001 RDX: 00000000b866b3b2 RSI: ffffffff8e6fc28f RDI: ffffffff8c6d9380 RBP: ffff88807715be80 R08: 8c00000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffff888066f6e418 R12: ffff888066f6e418 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000246 __raw_spin_lock include/linux/spinlock_api_smp.h:190 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173 spin_lock include/linux/spinlock.h:347 [inline] __io_cq_lock io_uring/io_uring.c:484 [inline] __io_submit_flush_completions+0x85/0x10d0 io_uring/io_uring.c:1133 io_submit_flush_completions io_uring/io_uring.h:253 [inline] io_submit_state_end io_uring/io_uring.c:1939 [inline] io_submit_sqes+0x1cec/0x2310 io_uring/io_uring.c:2063 __do_sys_io_uring_enter io_uring/io_uring.c:2637 [inline] __se_sys_io_uring_enter+0x35b/0x1bb0 io_uring/io_uring.c:2586 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f4a86d9e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4a87bdff38 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 0000200000000340 RCX: 00007f4a86d9e159 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000009 RBP: 0000000000000a12 R08: 0000000000000000 R09: 0000000000000008 R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000940 R13: 0000200000000948 R14: 0000000000000e26 R15: 0000000000000002 ---------------- Code disassembly (best guess): 0: eb 66 jmp 0x68 2: 85 db test %ebx,%ebx 4: 74 3e je 0x44 6: 83 fb 01 cmp $0x1,%ebx 9: 75 4c jne 0x57 b: e8 6b d2 e9 fc call 0xfce9d27b 10: 48 8d 3d f4 46 a7 0b lea 0xba746f4(%rip),%rdi # 0xba7470b 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 4a jmp 0x68 1e: e8 58 d2 e9 fc call 0xfce9d27b 23: 48 8d 3d f1 46 a7 0b lea 0xba746f1(%rip),%rdi # 0xba7471b * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 37 jmp 0x68 31: e8 45 d2 e9 fc call 0xfce9d27b 36: 48 8d 3d ee 46 a7 0b lea 0xba746ee(%rip),%rdi # 0xba7472b 3d: 67 addr32 3e: 48 rex.W 3f: 0f .byte 0xf --- 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