From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f79.google.com (mail-oo1-f79.google.com [209.85.161.79]) (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 6032524886A for ; Sat, 30 May 2026 05:55:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780120529; cv=none; b=TX+Pr1gvNuzgPMnm1zYFLYCfjn7uaUlf8h5u4s908VNOkHUNBmkqwuJAvBVcMLQazz8F3FeH5usEzYGwxgRgyXYb2iDo0oTqNGYW3cbs+Jum43e2cH9IAXa0WRj+ZFQjmjfON/bl1eCd2Md3wXkqMhXRBmZKV5tjguUNaDKtzCQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780120529; c=relaxed/simple; bh=EwrszXQ4S2FHDYbiBhzeDind2XSN+5k568R7ehjpp50=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=KkL8e5b6ffB3oDA90ouHe/QGw6LrofbrnFamzSZdn9HNywH6F61SITlpKCWcP2c4XT+k+sjpHAWbRo/3+U4Wt+kOfg1pDkiFlP8tsVXQ+g1G99FoYIhKjGELmiJNzedQEB3QZFpHFvLqBLneDuRS8UwBxjA12j5CgRPj0JZEM8M= 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=209.85.161.79 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-oo1-f79.google.com with SMTP id 006d021491bc7-69df6e55f3fso2755535eaf.3 for ; Fri, 29 May 2026 22:55:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780120527; x=1780725327; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=1m7I++Q6yyoUoXwVe9qgrro1GQAwLd9tdhMu6xnQm7U=; b=BN4jyuww5fsUFwuz5ZiDH01F26xXgI51kNQoG2quWfUPvk6q8jJ2SkYEvVfFJ5O50c 4/b4tW8/NI+C3cJSEur8hS+3I8knlILFdBX54zNtwHxZIMYt5ZGOqaQqcL8dyl1eOjN8 v7BpSzSyFCLSQuQhEf31K3BVBSbzpwvzgr5ra7XUch98uj7BwAulI8VZ7v6k9aV7w77f eNp/qAITsMIF3Bmfe6MpqD29Q68o1EFxOzKU3S/JyDUjf8jZ6vTaSyM8FkZGLpOfhHb4 QC6G9t9HP2UV2QgpEKuL7Fb4r/DkVrYgmX2kdlTa06GEMWgbYlOql0IFXcpGNPoIz49O GqpQ== X-Forwarded-Encrypted: i=1; AFNElJ/5Frn7f6Be2IwIoOIu6RYOiN1WXFG0pf5R4Dms3HunKtsnElhoyrwkMz/5mJ/EAqkigMdoOrGwvXWtrww=@vger.kernel.org X-Gm-Message-State: AOJu0YwDKUdxrJzw0AqTu1v5olzkUDftgrOORP36tXcToXOJ/WFUjBfs BjRSzB2ZBOVXp34tOChxLF2e0I7oPTjYHZiNJl+amjYKTT/5DAN1fvwi0DIkbBc9k9SDCWmYKhY 2eYyUhm7xh8hjcFiYrWoAUBzMtaWIegqKkrsi4xoWueU7EuxCjFW+Vz3Fim0= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1c8a:b0:69d:ce78:79a0 with SMTP id 006d021491bc7-69e105642f6mr1130878eaf.34.1780120527435; Fri, 29 May 2026 22:55:27 -0700 (PDT) Date: Fri, 29 May 2026 22:55:27 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a1a7bcf.0a9e871e.332604.000b.GAE@google.com> Subject: [syzbot] [net?] WARNING: refcount bug in __inet_csk_reqsk_queue_drop From: syzbot To: davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, kuniyu@google.com, linux-kernel@vger.kernel.org, ncardwell@google.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: eb3f4b7426cf Merge tag 'nfsd-7.1-2' of git://git.kernel.or.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11e5b673980000 kernel config: https://syzkaller.appspot.com/x/.config?x=bd38685893011045 dashboard link: https://syzkaller.appspot.com/bug?extid=e809069bc15f26300526 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3e8630fd2e70/disk-eb3f4b74.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3a23f2a3eb2a/vmlinux-eb3f4b74.xz kernel image: https://storage.googleapis.com/syzbot-assets/e102c22c34c3/bzImage-eb3f4b74.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+e809069bc15f26300526@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 ---------------- Code disassembly (best guess): 0: e4 7d in $0x7d,%al 2: d1 0a rorl $1,(%rdx) 4: 67 48 0f b9 3a ud1 (%edx),%rdi 9: eb 4a jmp 0x55 b: e8 38 3d 23 fd call 0xfd233d48 10: 48 8d 3d e1 7d d1 0a lea 0xad17de1(%rip),%rdi # 0xad17df8 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 37 jmp 0x55 1e: e8 25 3d 23 fd call 0xfd233d48 23: 48 8d 3d de 7d d1 0a lea 0xad17dde(%rip),%rdi # 0xad17e08 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 24 jmp 0x55 31: e8 12 3d 23 fd call 0xfd233d48 36: 48 8d 3d db 7d d1 0a lea 0xad17ddb(%rip),%rdi # 0xad17e18 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