From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-io1-f78.google.com (mail-io1-f78.google.com [209.85.166.78]) (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 992AA30BB9E for ; Mon, 10 Nov 2025 12:38:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762778307; cv=none; b=lHxD2HzdkZBivEF7m6lrPm5p8nKgelLCBM2x+Hp079rjii2gs2N1pOwmWDlbjOV1Te1GjBRXuo4DNhJsvlX57HV/3Lnssb0/sCl/h9+9BwsXf4+LZS5CIbnDjFNDHlNBsFnVuyKWJGfDCu987iNctamtDXwjNKlrRLbDgnOvUGw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762778307; c=relaxed/simple; bh=BCfvvEXeY6H6UtpuWIrt7AopHRQuvES0wL5swHqk7IU=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=SIAb57n/WzF5M7ZyOyBkrAxAI7lQEvv2Zh5uVnbMp3N7OFxPIA0TcSFSm9B2DEuZaBpdnfX9isk6SO9hjBCe/NdtjTuZaIgRgrZQvKFAGI9/AgLcI1xkQocTQFm6d0Ic2h1d5BupkXLLpBNA10nqAcdLxTx+jevxwD9w1A7EhTA= 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=209.85.166.78 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-io1-f78.google.com with SMTP id ca18e2360f4ac-9486ebd1e4dso277196839f.3 for ; Mon, 10 Nov 2025 04:38:25 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762778305; x=1763383105; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=pHR+NKBcK3L+aBXZ8xDlwRY8dl6XpDqfRmEc/iDSCro=; b=JsdVYqLMr8/4SX+CkCw/tU9Vjq3FOCvESd8F1XkHb0D0RVA3YAH/mkk60A2vNMJdpV s8QLuCMqe1ca+0QKEoVvDzsg6+MmCYDieeNoJrDO7huTYzYX/fWV3eqI8AYtUM1TQv0m fi7rqL3pFmcV4dd24DxM+/VWiQGKq12rLgx6YhqEedCfCI+GkGPGTsaU/dPa1l2XhaLi WaQ4oAmIbVZKfeAdb+pk0OkP6G/ituV5s8CZnXwge71beUuE6b8HfR2ISE8PtnJhsP1v KESe31GkZ+pvcVwl8oFh/0HbhOZLL4E1SULz710NHIsvC4KcFxJuA3DHzoV9f4VnDxW+ MnRg== X-Forwarded-Encrypted: i=1; AJvYcCWMYqh/xi3sjOfQjK3GWGvRDa+WM2BjPBeE1uQJrms6z7mYAR4pjIFp3UepSEtI4R96+jTswb4ad51IrGE=@vger.kernel.org X-Gm-Message-State: AOJu0YyjUnwjoU3giWL0COHhwLLBuRANXSMUC6DTlZiZMsdAZONNLDau fnTsd3G0Q1p8PvpTUQkzN7sDdf8lU4mhclFJm7RsdQl6sQqCybe2zW0iHwGWYlOFDdv0gYoXlRV HqoYjKWg2Y9YQ9RP9pIbJXsudt+MyqhMgSSMwqY8OvmlehwzOhmJZbapxqow= X-Google-Smtp-Source: AGHT+IFlI1SjeIah8QgfxOkQEjEn2ZZ/BPy3jVI577kmaDWdgotXOaJaP6omqG9s88pi9hMgFMpQTrQuAwBkDLjwI843DpyIskJ6 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:1c23:b0:433:2fa2:a55d with SMTP id e9e14a558f8ab-43367de53edmr133878845ab.12.1762778304716; Mon, 10 Nov 2025 04:38:24 -0800 (PST) Date: Mon, 10 Nov 2025 04:38:24 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6911dcc0.a70a0220.22f260.00ed.GAE@google.com> Subject: [syzbot] [fs?] KASAN: null-ptr-deref Read in drop_buffers (5) From: syzbot To: brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 7bb4d6512545 Merge tag 'v6.18rc4-SMB-client-fixes' of git:.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17170412580000 kernel config: https://syzkaller.appspot.com/x/.config?x=b944b1e5afd39857 dashboard link: https://syzkaller.appspot.com/bug?extid=e07658f51ca22ab65b4e compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/f75c0b0bb6c3/disk-7bb4d651.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f7a1ee597ee0/vmlinux-7bb4d651.xz kernel image: https://storage.googleapis.com/syzbot-assets/bd9a86dba20d/bzImage-7bb4d651.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+e07658f51ca22ab65b4e@syzkaller.appspotmail.com ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: null-ptr-deref in buffer_busy fs/buffer.c:2886 [inline] BUG: KASAN: null-ptr-deref in drop_buffers.constprop.0+0x89/0x340 fs/buffer.c:2898 Read of size 4 at addr 0000000000000060 by task kswapd0/85 CPU: 0 UID: 0 PID: 85 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 kasan_report+0xe0/0x110 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:194 [inline] kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:200 instrument_atomic_read include/linux/instrumented.h:68 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] buffer_busy fs/buffer.c:2886 [inline] drop_buffers.constprop.0+0x89/0x340 fs/buffer.c:2898 try_to_free_buffers+0x21c/0x2d0 fs/buffer.c:2952 filemap_release_folio+0x219/0x280 mm/filemap.c:4423 shrink_folio_list+0x28a5/0x4800 mm/vmscan.c:1519 evict_folios+0x79c/0x1b30 mm/vmscan.c:4745 try_to_shrink_lruvec+0x585/0x9b0 mm/vmscan.c:4908 shrink_one+0x3e3/0x7a0 mm/vmscan.c:4953 shrink_many mm/vmscan.c:5016 [inline] lru_gen_shrink_node mm/vmscan.c:5094 [inline] shrink_node+0x26cb/0x3d80 mm/vmscan.c:6081 kswapd_shrink_node mm/vmscan.c:6941 [inline] balance_pgdat+0xbb8/0x1a50 mm/vmscan.c:7124 kswapd+0x590/0xb90 mm/vmscan.c:7389 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 ================================================================== Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067] CPU: 0 UID: 0 PID: 85 Comm: kswapd0 Tainted: G B syzkaller #0 PREEMPT(full) Tainted: [B]=BAD_PAGE Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline] RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline] RIP: 0010:buffer_busy fs/buffer.c:2886 [inline] RIP: 0010:drop_buffers.constprop.0+0x90/0x340 fs/buffer.c:2898 Code: 4d 8b 76 08 4c 39 f3 0f 84 84 00 00 00 e8 f8 28 72 ff 4d 8d 66 60 be 04 00 00 00 4c 89 e7 e8 d7 cc d9 ff 4c 89 e0 48 c1 e8 03 <0f> b6 0c 28 4c 89 e0 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85 2d RSP: 0018:ffffc9000239f0b0 EFLAGS: 00010216 RAX: 000000000000000c RBX: ffff888057ccd3e0 RCX: ffffffff817b40ef RDX: ffff88801ef18000 RSI: ffffffff82246d87 RDI: 0000000000000007 RBP: dffffc0000000000 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: 3d3d3d3d3d3d3d3d R12: 0000000000000060 R13: ffffea0000a77880 R14: 0000000000000000 R15: ffffea0000a778a8 FS: 0000000000000000(0000) GS:ffff888124a07000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e34233c168 CR3: 0000000030ecb000 CR4: 0000000000350ef0 Call Trace: try_to_free_buffers+0x21c/0x2d0 fs/buffer.c:2952 filemap_release_folio+0x219/0x280 mm/filemap.c:4423 shrink_folio_list+0x28a5/0x4800 mm/vmscan.c:1519 evict_folios+0x79c/0x1b30 mm/vmscan.c:4745 try_to_shrink_lruvec+0x585/0x9b0 mm/vmscan.c:4908 shrink_one+0x3e3/0x7a0 mm/vmscan.c:4953 shrink_many mm/vmscan.c:5016 [inline] lru_gen_shrink_node mm/vmscan.c:5094 [inline] shrink_node+0x26cb/0x3d80 mm/vmscan.c:6081 kswapd_shrink_node mm/vmscan.c:6941 [inline] balance_pgdat+0xbb8/0x1a50 mm/vmscan.c:7124 kswapd+0x590/0xb90 mm/vmscan.c:7389 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline] RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline] RIP: 0010:buffer_busy fs/buffer.c:2886 [inline] RIP: 0010:drop_buffers.constprop.0+0x90/0x340 fs/buffer.c:2898 Code: 4d 8b 76 08 4c 39 f3 0f 84 84 00 00 00 e8 f8 28 72 ff 4d 8d 66 60 be 04 00 00 00 4c 89 e7 e8 d7 cc d9 ff 4c 89 e0 48 c1 e8 03 <0f> b6 0c 28 4c 89 e0 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85 2d RSP: 0018:ffffc9000239f0b0 EFLAGS: 00010216 RAX: 000000000000000c RBX: ffff888057ccd3e0 RCX: ffffffff817b40ef RDX: ffff88801ef18000 RSI: ffffffff82246d87 RDI: 0000000000000007 RBP: dffffc0000000000 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: 3d3d3d3d3d3d3d3d R12: 0000000000000060 R13: ffffea0000a77880 R14: 0000000000000000 R15: ffffea0000a778a8 FS: 0000000000000000(0000) GS:ffff888124a07000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e34233c168 CR3: 0000000030ecb000 CR4: 0000000000350ef0 ---------------- Code disassembly (best guess): 0: 4d 8b 76 08 mov 0x8(%r14),%r14 4: 4c 39 f3 cmp %r14,%rbx 7: 0f 84 84 00 00 00 je 0x91 d: e8 f8 28 72 ff call 0xff72290a 12: 4d 8d 66 60 lea 0x60(%r14),%r12 16: be 04 00 00 00 mov $0x4,%esi 1b: 4c 89 e7 mov %r12,%rdi 1e: e8 d7 cc d9 ff call 0xffd9ccfa 23: 4c 89 e0 mov %r12,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 0f b6 0c 28 movzbl (%rax,%rbp,1),%ecx <-- trapping instruction 2e: 4c 89 e0 mov %r12,%rax 31: 83 e0 07 and $0x7,%eax 34: 83 c0 03 add $0x3,%eax 37: 38 c8 cmp %cl,%al 39: 7c 08 jl 0x43 3b: 84 c9 test %cl,%cl 3d: 0f .byte 0xf 3e: 85 .byte 0x85 3f: 2d .byte 0x2d --- 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