linux-kernel - Re: [syzbot] [gfs2?] UBSAN: shift-out-of-bounds in gfs2_dir

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Message-ID: <68764d4f.a70a0220.693ce.000a.GAE@google.com>
Date: Tue, 15 Jul 2025 05:45:03 -0700
From: syzbot <syzbot+4708579bb230a0582a57@...kaller.appspotmail.com>
To: agruenba@...hat.com, anprice@...hat.com, gfs2@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [gfs2?] UBSAN: shift-out-of-bounds in gfs2_dir_read (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in move_to_new_folio

------------[ cut here ]------------
gfs2_meta_aops does not implement migrate_folio
WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 fallback_migrate_folio mm/migrate.c:942 [inline]
WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
Modules linked in:
CPU: 0 UID: 0 PID: 30 Comm: kcompactd1 Not tainted 6.16.0-rc6-syzkaller-g155a3c003e55-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:fallback_migrate_folio mm/migrate.c:942 [inline]
RIP: 0010:move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
Code: 0d 01 90 42 80 7c 3d 00 00 74 0a 48 8b 7c 24 20 e8 2f 53 fe ff 48 8b 44 24 20 48 8b 30 48 c7 c7 20 bb 97 8b e8 cb b5 5e ff 90 <0f> 0b 90 90 49 bf 00 00 00 00 00 fc ff df e9 7e fd ff ff e8 e2 d2
RSP: 0018:ffffc90000516fd0 EFLAGS: 00010246
RAX: 0ac1efce833f5700 RBX: ffffea0000d5d100 RCX: ffff888030f20000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 1ffff1100aaeabc5 R08: ffff88801fc24293 R09: 1ffff11003f84852
R10: dffffc0000000000 R11: ffffed1003f84853 R12: ffffea00015c8e00
R13: ffff888055755d08 R14: ffffea0000d5d108 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88808d21b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffb6eacfe8 CR3: 0000000054de7000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 migrate_folio_move mm/migrate.c:1301 [inline]
 migrate_folios_move mm/migrate.c:1653 [inline]
 migrate_pages_batch+0x1c34/0x2830 mm/migrate.c:1900
 migrate_pages_sync mm/migrate.c:1930 [inline]
 migrate_pages+0x1bcc/0x2930 mm/migrate.c:2039
 compact_zone+0x23f4/0x4ad0 mm/compaction.c:2683
 compact_node+0x1d2/0x280 mm/compaction.c:2952
 kcompactd+0xbc8/0x1290 mm/compaction.c:3250
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


Tested on:

commit:         155a3c00 Merge tag 'for-6.16/dm-fixes-2' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11eb8382580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f62a2ef17395702a
dashboard link: https://syzkaller.appspot.com/bug?extid=4708579bb230a0582a57
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=150808f0580000