From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) (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 E19F93C17 for ; Sat, 21 Feb 2026 22:24:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771712669; cv=none; b=Q9O8FDY90n1RSXYgFqImVLZTBpoTMVs53jCCuNGM27QaxYKVNvbzaGHLJwl0rTZ5ce0DiziqGO/0LTKF3mtnLAV3zuedvL4scE+xhhu6Sl6yErBRKtjiWgIOwinfxtu9+EP2P2wjc6WCIbpPbGbuAhH5lwhhQ8hhbz/d9+daL2w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771712669; c=relaxed/simple; bh=aeh6i58Bb1YcPIZer3SR6lHi/FLThxRL4BocdX+ERdM=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=YlJfUD6vO3MZzx2aVmm6yYHutOl11O9v2eWItOpVqIU2G7ffj/3wll2az53azcD2KUCAE3K9euulUPOKguK3sh77dQ14OE4nSjuD/XMfpVMcqKrrmcK6WmbDCm6uCXoV2gD8HXafrIMCs7F2wByr8WAame3D9Hk5ZP32VYeCgss= 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=209.85.161.69 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-f69.google.com with SMTP id 006d021491bc7-679943693c0so53497581eaf.3 for ; Sat, 21 Feb 2026 14:24:27 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771712667; x=1772317467; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=b4I97kyRF6zNjRiiT3Q6lTqxeSzAqTCbveJzfDz68tI=; b=XPGzzgR6tViuCEHo/YLDDfMVIlHElRW1NMS04LIQj8y+0B5NdwS7nA9nboMLvMOS3v knqEWO1DyIhdN40OyJsJ/uBMQDblYw/YGBAjpzNYT4eAqC2I17NLr35fs52kjbB8MBX/ IW0Lxy0jLQhxaetKbU8mKY/EhPfNl0JksWS6MMTqcSkmQgZNICJ2Csnc46h//+pjTt8S oqPeFG2aDwj5nnaO5omPur2WOk5ax/wYbvI+OlJE3SdItHNXGHDFQvigMfFYarCrKwIT J7C+wDxodj560Re+x5h9thq9NfYBV/ck8i/+HhLpd1JtPdVc7VzhbsGt9pEHG7SUumUS NVfA== X-Forwarded-Encrypted: i=1; AJvYcCUXCqeceFsv1vR5bzDmd2bnQDnw2RCeh8uffazDKbmcF/gYw+AvoRKHkcZKR+V9SZAB1wMdPWo=@vger.kernel.org X-Gm-Message-State: AOJu0YwNFKO+kbt3NfGW+tMwP0xiYqfMdJICLPctYLCn6mWefPuA7Rwl S5woBky5SNl8R147pTfkCbS3ZvacF5UVBCYXmxWrn/ib5nIRBAahURl50gamq8Tr1G/5m+KBHTF K10241pIhYSFRb4yZ7a3H8IkRTtvFbMdrLYmnOeEIv7fXaiLgcE9Nm9mY2iY= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:16a3:b0:679:94ff:6ea7 with SMTP id 006d021491bc7-679c4251e3dmr2394455eaf.15.1771712666946; Sat, 21 Feb 2026 14:24:26 -0800 (PST) Date: Sat, 21 Feb 2026 14:24:26 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <699a309a.a70a0220.2c38d7.0165.GAE@google.com> Subject: [syzbot] [net?] [trace?] WARNING: refcount bug in call_timer_fn (4) From: syzbot To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, netdev@vger.kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 8b690556d8fe Merge tag 'for-linus' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11715658580000 kernel config: https://syzkaller.appspot.com/x/.config?x=38a0c4cddc846161 dashboard link: https://syzkaller.appspot.com/bug?extid=07dcf509f4c013e25dc5 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3ca2379f6d75/disk-8b690556.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/ce7e9a97f8b4/vmlinux-8b690556.xz kernel image: https://storage.googleapis.com/syzbot-assets/0936d2c0b069/bzImage-8b690556.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+07dcf509f4c013e25dc5@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 29 at lib/refcount.c:28 refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28 Modules linked in: CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:refcount_warn_saturate+0x11a/0x1d0 lib/refcount.c:28 Code: c0 30 3d 8b e8 c7 91 09 fd 90 0f 0b 90 90 eb d7 e8 ab 4a 45 fd c6 05 10 1a 47 0a 01 90 48 c7 c7 20 31 3d 8b e8 a7 91 09 fd 90 <0f> 0b 90 90 eb b7 e8 8b 4a 45 fd c6 05 ed 19 47 0a 01 90 48 c7 c7 RSP: 0018:ffffc90000a3f888 EFLAGS: 00010246 RAX: 74da3aaac3757600 RBX: 0000000000000003 RCX: ffff88801be99e00 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100 RBP: ffffc90000a3f990 R08: 0000000000000000 R09: 0000000000000100 R10: dffffc0000000000 R11: ffffed101712487b R12: 1ffff92000147f18 R13: ffff88805d5311b8 R14: ffff88805d531020 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888126ef7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000404030 CR3: 000000000d3a6000 CR4: 00000000003526f0 Call Trace: call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747 expire_timers kernel/time/timer.c:1798 [inline] __run_timers kernel/time/timer.c:2372 [inline] __run_timer_base+0x648/0x970 kernel/time/timer.c:2384 run_timer_base kernel/time/timer.c:2393 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403 handle_softirqs+0x22f/0x710 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0xcf/0x190 kernel/softirq.c:1138 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- 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