From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) (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 61D5E346ADA for ; Sat, 6 Jun 2026 13:33:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780752786; cv=none; b=DKkYuJqz5D8Z+7IP58JP8j7jbRanCEP3o9mOeHVcsGZXtte/XI0tfGpkMVw1E+hOuyEGTqlaLK2lZSsfrS6u9HKblq8q88d3/5KaFeZupow71AQ76xU8NDtcra0TVvdt7q4G3lAOJZDWBMv6QrBJYMICgGcE918oKGHFsQIWPHw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780752786; c=relaxed/simple; bh=GPBHtX9d4uZgpmLjCIITIULtcx7OukPSWjpqO1Df2Rs=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=AWUOPhJvFWZjltEQDJBWnkktobiHDLuS2HLZycAwGSBK5Lnc5k+EOhRO/gT5gSkN6yx6jfRd07Z5PJy8bDStxplMcG6z4krW5KDAnaW5OSBPwxW83CDcNSTESiG9ARvsldeBYT7wK6n11gvfnVzCWnpB1w8xJJuANYVmzwONwB8= 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=209.85.161.70 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-f70.google.com with SMTP id 006d021491bc7-69de23f28d5so3979060eaf.2 for ; Sat, 06 Jun 2026 06:33:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780752784; x=1781357584; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=49LJU4IPEunDLDRJZ0Z8NrvNHANlpR3gRJ2mNXfQk98=; b=LvfXeY1Mers1crBRDNT7lOfWvgQsSNkAFawf80he8fkpC/nqXvOJXyPO2hn/sAz3ql qz0MPiPlfC+0VBVIvopBXpxR85KUq933kWT5K0OvxHQ6IjH36Ir/8z1R6c3cNJJ2Xez7 mPUkvvDugM4IKkOx6buxm/52yN+W94If8lrD7f5sxL4XmVowc04Qs9ZfCKPlbne2RRXQ YhPF4Zp7S2iz3zNGGEogv+HnKC1lPZcgY9Ok01HzX9Q9AVrGtPPecOx/awMvv18Yailu CDuenP8xtRK8xMdBJzfFlYLAJeegpxZvAOux3AKR7Mflbq0x4HIfJ1ONBLxvNSTsQPly plgQ== X-Forwarded-Encrypted: i=1; AFNElJ9XEINOIIlKwkiWVguLmBZD7zwcMYaFAmwljdku+F349Oj3+2m3LPFCdkKJ87OdKaJRsSHXN0RAiaysiu8=@vger.kernel.org X-Gm-Message-State: AOJu0Yysw9XV/hF6bY3TiXgvWSN5RG5CXaJ8w4hug/9frFGeoRTLHcf/ ea/fkHmJ7LJX9y8W9GMHJ52xtwmNyEMlVGIJpYByfZP/7f5+gS7/AodvSOmS2Fa7bTcLDfdyTaH IxBIpP7+IVh0tlYMeli6NE5MPqq0rO4G3DS2mLUk4jSJ6sovH5QxAzHNkHhE= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1512:b0:696:17a6:c06f with SMTP id 006d021491bc7-69e68b1b340mr4537236eaf.12.1780752784249; Sat, 06 Jun 2026 06:33:04 -0700 (PDT) Date: Sat, 06 Jun 2026 06:33:04 -0700 In-Reply-To: <20260606131125.1604-1-hdanton@sina.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a242190.e4db5ad2.3b7dfb.0006.GAE@google.com> Subject: Re: [syzbot] [v9fs?] WARNING: refcount bug in p9_req_put (4) From: syzbot To: hdanton@sina.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: WARNING: refcount bug in p9_req_put ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x130 lib/refcount.c:28, CPU#3: swapper/3/0 Modules linked in: CPU: 3 UID: 0 PID: 0 Comm: swapper/3 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+0xf4/0x130 lib/refcount.c:28 Code: cc e8 10 53 0f fd 48 8d 3d 89 4c e8 0b 67 48 0f b9 3a e8 ff 52 0f fd 5b 5d e9 d8 5f 93 06 e8 f3 52 0f fd 48 8d 3d 7c 4c e8 0b <67> 48 0f b9 3a e8 e2 52 0f fd 5b 5d c3 cc cc cc cc e8 d6 52 0f fd RSP: 0018:ffffc900006f8d90 EFLAGS: 00010046 RAX: 0000000080010002 RBX: ffff8880341eb658 RCX: ffffffff84f95c3b RDX: ffff88801eac2540 RSI: ffffffff84f95ccd RDI: ffffffff90e1a950 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000004 R10: 0000000000000003 R11: 0000000000000001 R12: ffff8880341eb658 R13: ffff8880287ccc00 R14: 000000000000000b R15: 1ffff1100465880c FS: 0000000000000000(0000) GS:ffff8880d6687000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00001e1e2cc78000 CR3: 00000000389b6000 CR4: 0000000000352ef0 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] p9_req_put+0x1ec/0x250 net/9p/client.c:276 req_done+0x1dc/0x2e0 net/9p/trans_virtio.c:147 vring_interrupt+0x2ef/0x650 drivers/virtio/virtio_ring.c:3254 __handle_irq_event_percpu+0x235/0x8c0 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:263 handle_edge_irq+0x35e/0x960 kernel/irq/chip.c:857 generic_handle_irq_desc include/linux/irqdesc.h:186 [inline] handle_irq arch/x86/kernel/irq.c:262 [inline] call_irq_handler arch/x86/kernel/irq.c:318 [inline] __common_interrupt+0xd8/0x2f0 arch/x86/kernel/irq.c:333 common_interrupt+0xb9/0xe0 arch/x86/kernel/irq.c:326 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63 Code: a6 92 02 e9 43 44 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 23 02 22 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc90000197df0 EFLAGS: 00000202 RAX: 0000000000162557 RBX: ffff88801eac2540 RCX: ffffffff8b899225 RDX: 0000000000000000 RSI: ffffffff8df0fbdb RDI: ffffffff8c1c4680 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed100d4e67b5 R10: ffff88806a733dab R11: 0000000000000000 R12: 0000000000000003 R13: ffffed1003d584a8 R14: 0000000000000003 R15: ffffffff90d71950 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline] default_idle+0x9/0x10 arch/x86/kernel/process.c:767 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x464/0x590 kernel/sched/idle.c:352 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x148 ---------------- Code disassembly (best guess): 0: cc int3 1: e8 10 53 0f fd call 0xfd0f5316 6: 48 8d 3d 89 4c e8 0b lea 0xbe84c89(%rip),%rdi # 0xbe84c96 d: 67 48 0f b9 3a ud1 (%edx),%rdi 12: e8 ff 52 0f fd call 0xfd0f5316 17: 5b pop %rbx 18: 5d pop %rbp 19: e9 d8 5f 93 06 jmp 0x6935ff6 1e: e8 f3 52 0f fd call 0xfd0f5316 23: 48 8d 3d 7c 4c e8 0b lea 0xbe84c7c(%rip),%rdi # 0xbe84ca6 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e8 e2 52 0f fd call 0xfd0f5316 34: 5b pop %rbx 35: 5d pop %rbp 36: c3 ret 37: cc int3 38: cc int3 39: cc int3 3a: cc int3 3b: e8 d6 52 0f fd call 0xfd0f5316 Tested on: commit: 8e65320d Merge tag 'drm-fixes-2026-06-06' of https://g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11f57166580000 kernel config: https://syzkaller.appspot.com/x/.config?x=8118209836970b54 dashboard link: https://syzkaller.appspot.com/bug?extid=f6fdb3bdd2c1d419e263 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 patch: https://syzkaller.appspot.com/x/patch.diff?x=1705eb7e580000