Message-ID: <CAKFNMonk7-DOE_knZLG8N_JijauKZ-DLgfA9GwsU0nDsbjKcSw@mail.gmail.com>
Date: Mon, 21 Oct 2024 19:57:32 +0900
From: Ryusuke Konishi <konishi.ryusuke@...il.com>
To: syzbot <syzbot+985ada84bf055a575c07@...kaller.appspotmail.com>
Cc: akpm@...ux-foundation.org, brauner@...nel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-nilfs@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [nilfs] [fs] kernel BUG in submit_bh_wbc (3)

On Mon, Oct 21, 2024 at 6:48 PM syzbot
<syzbot+985ada84bf055a575c07@...kaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    42f7652d3eb5 Linux 6.12-rc4
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=10c66a40580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=41330fd2db03893d
> dashboard link: https://syzkaller.appspot.com/bug?extid=985ada84bf055a575c07
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1541e430580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1181e0a7980000

The kernel bug reproduced by this C-reproducer is fixed by the patch
"nilfs2: fix kernel bug due to missing clearing of buffer delay flag"
on the way upstream.  I actually performed a follow-up test of this
C-reproducer and confirmed it.

This should be closed by the patch, so although there are additional
messages sent by syzbot, I will leave it without closing it manually.

Ryusuke Konishi


>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/21f56ec05989/disk-42f7652d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d295ea00e68a/vmlinux-42f7652d.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6c4b95c7f67f/bzImage-42f7652d.xz
> mounted in repro #1: https://storage.googleapis.com/syzbot-assets/709e6e32762f/mount_0.gz
> mounted in repro #2: https://storage.googleapis.com/syzbot-assets/6576d8861c23/mount_7.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+985ada84bf055a575c07@...kaller.appspotmail.com
>
> ------------[ cut here ]------------
> kernel BUG at fs/buffer.c:2785!
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> CPU: 0 UID: 0 PID: 5235 Comm: syz-executor372 Not tainted 6.12.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> RIP: 0010:submit_bh_wbc+0x556/0x560 fs/buffer.c:2785
> Code: 89 fa e8 dd 76 cc 02 e9 95 fe ff ff e8 73 85 74 ff 90 0f 0b e8 6b 85 74 ff 90 0f 0b e8 63 85 74 ff 90 0f 0b e8 5b 85 74 ff 90 <0f> 0b e8 53 85 74 ff 90 0f 0b 90 90 90 90 90 90 90 90 90 90 90 90
> RSP: 0018:ffffc90003b6f0d8 EFLAGS: 00010293
> RAX: ffffffff82206235 RBX: 0000000000000154 RCX: ffff88802d490000
> RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000
> RBP: 0000000000000100 R08: ffffffff82205df9 R09: 1ffff1100ef571d0
> R10: dffffc0000000000 R11: ffffed100ef571d1 R12: 0000000000000000
> R13: ffff888077ab8e80 R14: 0000000000000000 R15: 1ffff1100ef571d0
> FS:  0000555573f7e380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fbda422e00a CR3: 000000002fc1e000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  submit_bh fs/buffer.c:2824 [inline]
>  block_read_full_folio+0x93b/0xcd0 fs/buffer.c:2451
>  do_mpage_readpage+0x1a73/0x1c80 fs/mpage.c:317
>  mpage_read_folio+0x108/0x1e0 fs/mpage.c:392
>  filemap_read_folio+0x14b/0x630 mm/filemap.c:2367
>  do_read_cache_folio+0x3f5/0x850 mm/filemap.c:3825
>  read_mapping_folio include/linux/pagemap.h:1011 [inline]
>  nilfs_get_folio+0x4b/0x240 fs/nilfs2/dir.c:190
>  nilfs_find_entry+0x13d/0x660 fs/nilfs2/dir.c:313
>  nilfs_inode_by_name+0xad/0x240 fs/nilfs2/dir.c:394
>  nilfs_lookup+0xed/0x210 fs/nilfs2/namei.c:63
>  lookup_open fs/namei.c:3573 [inline]
>  open_last_lookups fs/namei.c:3694 [inline]
>  path_openat+0x11a7/0x3590 fs/namei.c:3930
>  do_filp_open+0x235/0x490 fs/namei.c:3960
>  do_sys_openat2+0x13e/0x1d0 fs/open.c:1415
>  do_sys_open fs/open.c:1430 [inline]
>  __do_sys_openat fs/open.c:1446 [inline]
>  __se_sys_openat fs/open.c:1441 [inline]
>  __x64_sys_openat+0x247/0x2a0 fs/open.c:1441
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fbda41e54a9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe5e610168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fbda41e54a9
> RDX: 000000000000275a RSI: 0000000020000180 RDI: 00000000ffffff9c
> RBP: 0000000000000000 R08: 00000000000051a5 R09: 000000002000a440
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe5e61019c
> R13: 0000000000000007 R14: 431bde82d7b634db R15: 00007ffe5e6101d0
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:submit_bh_wbc+0x556/0x560 fs/buffer.c:2785
> Code: 89 fa e8 dd 76 cc 02 e9 95 fe ff ff e8 73 85 74 ff 90 0f 0b e8 6b 85 74 ff 90 0f 0b e8 63 85 74 ff 90 0f 0b e8 5b 85 74 ff 90 <0f> 0b e8 53 85 74 ff 90 0f 0b 90 90 90 90 90 90 90 90 90 90 90 90
> RSP: 0018:ffffc90003b6f0d8 EFLAGS: 00010293
> RAX: ffffffff82206235 RBX: 0000000000000154 RCX: ffff88802d490000
> RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000
> RBP: 0000000000000100 R08: ffffffff82205df9 R09: 1ffff1100ef571d0
> R10: dffffc0000000000 R11: ffffed100ef571d1 R12: 0000000000000000
> R13: ffff888077ab8e80 R14: 0000000000000000 R15: 1ffff1100ef571d0
> FS:  0000555573f7e380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fbd9cbff000 CR3: 000000002fc1e000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> 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.

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