From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f79.google.com (mail-oa1-f79.google.com [209.85.160.79]) (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 A51D518B0A for ; Wed, 29 Jul 2026 00:08:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785283713; cv=none; b=dzl/8aQDkrTOSas5krbM5sKb8EIF50C7aIztIw2zVvz+QL2Ulp0An3W0QeDGVIeK0GfHX3oxdb8dWuDOhVuTx2w0PqYbzPkbn3IlIGxRkgblAR92bjb65GO+oRHqXfjp7EUvf+O8ByquYaLtnbi5Wlq1p5wO3dtyMrqm+LovCB4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785283713; c=relaxed/simple; bh=m15/uLQUzt1/qMxqLD5P4CFQbcibhOAPueOU1QolVns=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=iOnoCpFkcUpQciyp14aI7QumPy97JjYocQFw+T+PT7qb6iDAqtRQXhYh7ByJClTQFvMY1k8fDXr9xibOc4M/z6e/6+PBXMnw/w8zHo4y8eYa/t4yqVfPmW11BtbnYLNyldrsF2YeBDddrK+JrLpLlm1/Lq3FCVqYyCEaceZFpj4= 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=209.85.160.79 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-oa1-f79.google.com with SMTP id 586e51a60fabf-43cd2d12617so427286fac.3 for ; Tue, 28 Jul 2026 17:08:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785283710; x=1785888510; 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=sQfd443m869Z315NskmbdGV/Ciywl9JKFn4B+STkpGc=; b=OeQqZPYvGMMaj0nim8tcHRoHQ7ty+EtdWK3MGBG1mb/lMvNu5y+yHSQND7qpvxPYOB 9fMBCn/FBgxWH+TF4y/ockKvHPI2gE9nS5lXoBw8CmGnlVy43hWn7SaKcVN8oYleh63a StwjNuWEnRgdE46OlW83hxBJa1wpy1idFOfE8P40GevNFgTfJH6gIdC5iQsSkWhgbApf GpVIID5j8f89qEq8ncpeqqhZWG0z0X4OsKMs+beT2LxWWUpeml51og9bp7vsCO6G7jCf WtpIPiAT7zz6QM74hN4EwDr7U7pznDWoAtNu2QrxN1jvLqcSxz7gcLaGfjdgIbK/kcwd cZmA== X-Forwarded-Encrypted: i=1; AHgh+RqKU8pnS1JzuhWELXbXBHI9tIV14M4j75rJG4/p3HcJoJ0gRzJ+oWy2dqEYOoFb+xphQOl5gGZDQFIrqeA=@vger.kernel.org X-Gm-Message-State: AOJu0YzYopi/Y1c6ZtwKi5xh83e3MARcICuo63UfybmZ0Lx9BvD9zUWp D6gvBTIYitnIxeZIg+Tb3A1qYl2hnnmgT6MkFT3L+HocxXNvcBWFuPzNbXlbArmsVqRtWVqYYM6 QsTIEGPLB/gV8xsPp6P9hsi5VDv7xuNt1huVRrVlGyJcIK36+DSz7vXR/JDM= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:130a:b0:48b:17c4:3572 with SMTP id 5614622812f47-4ad5b9e93acmr2896992b6e.29.1785283710551; Tue, 28 Jul 2026 17:08:30 -0700 (PDT) Date: Tue, 28 Jul 2026 17:08:30 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a69447e.6bd615f2.c0aa.0000.GAE@google.com> Subject: [syzbot] [fs?] WARNING: refcount bug in config_item_get From: syzbot To: a.hindborg@kernel.org, leitao@debian.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 0ce37745d4bf Merge tag 'block-7.2-20260724' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1752909e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a dashboard link: https://syzkaller.appspot.com/bug?extid=35790eb7861f8fc57382 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13603fde580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1147e1b9580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c6e920012605/disk-0ce37745.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f5c4d270d5f3/vmlinux-0ce37745.xz kernel image: https://storage.googleapis.com/syzbot-assets/9e5e96acc1aa/bzImage-0ce37745.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+35790eb7861f8fc57382@syzkaller.appspotmail.com Mass Storage Function, version: 2009/09/11 LUN: removable file: (no medium) ------------[ 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#0: syz.4.481/6445 Modules linked in: CPU: 0 UID: 0 PID: 6445 Comm: syz.4.481 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 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 bb cc 02 fd 48 8d 3d 64 60 f7 0a 67 48 0f b9 3a eb 4a e8 a8 cc 02 fd 48 8d 3d 61 60 f7 0a <67> 48 0f b9 3a eb 37 e8 95 cc 02 fd 48 8d 3d 5e 60 f7 0a 67 48 0f RSP: 0018:ffffc90004777c48 EFLAGS: 00010293 RAX: ffffffff84c2fbe8 RBX: 0000000000000002 RCX: ffff88802809be00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8fba5c50 RBP: 0000000000000000 R08: ffff88802809be00 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: dffffc0000000000 R13: ffff888042748fb0 R14: ffff888034a6d424 R15: 1ffff920008eefa0 FS: 00005555785d9500(0000) GS:ffff888125c42000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc5c2af56b8 CR3: 00000000421ca000 CR4: 00000000003526f0 Call Trace: __refcount_add include/linux/refcount.h:-1 [inline] __refcount_inc include/linux/refcount.h:366 [inline] refcount_inc include/linux/refcount.h:383 [inline] kref_get include/linux/kref.h:45 [inline] config_item_get+0x88/0x90 fs/configfs/item.c:104 configfs_get_config_item fs/configfs/configfs_internal.h:127 [inline] get_target fs/configfs/symlink.c:128 [inline] configfs_symlink+0x4ab/0x1030 fs/configfs/symlink.c:185 vfs_symlink+0x18b/0x330 fs/namei.c:5660 filename_symlinkat+0x1cd/0x420 fs/namei.c:5685 __do_sys_symlinkat fs/namei.c:5705 [inline] __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5700 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb94cbede99 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:00007ffeae1a3f68 EFLAGS: 00000246 ORIG_RAX: 000000000000010a RAX: ffffffffffffffda RBX: 00007fb94ce75fa0 RCX: 00007fb94cbede99 RDX: 0000200000000300 RSI: ffffffffffffff9c RDI: 0000200000000200 RBP: 00007fb94cc83eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb94ce75fac R14: 00007fb94ce75fa0 R15: 00007fb94ce75fa0 ---------------- 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 bb cc 02 fd call 0xfd02cccb 10: 48 8d 3d 64 60 f7 0a lea 0xaf76064(%rip),%rdi # 0xaf7607b 17: 67 48 0f b9 3a ud1 (%edx),%rdi 1c: eb 4a jmp 0x68 1e: e8 a8 cc 02 fd call 0xfd02cccb 23: 48 8d 3d 61 60 f7 0a lea 0xaf76061(%rip),%rdi # 0xaf7608b * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb 37 jmp 0x68 31: e8 95 cc 02 fd call 0xfd02cccb 36: 48 8d 3d 5e 60 f7 0a lea 0xaf7605e(%rip),%rdi # 0xaf7609b 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 syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. 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