KASAN: slab-use-after-free Read in gfs2_invalidate_folio (2)

Status: upstream: reported on 2026/08/31 10:27
Reported-by: syzbot+e6aecaf4c47dc4f22a07@syzkaller.appspotmail.com
First crash: 27d, last: 14d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in gfs2_invalidate_folio 19 22 177d 419d 0/2 auto-obsoleted due to no activity on 2026/07/12 16:28
upstream KASAN: slab-use-after-free Read in gfs2_invalidate_folio prio:high gfs2 19 syz, C error 174 173d 899d 0/29 upstream: reported C repro on 2024/04/11 16:17
linux-6.1 KASAN: use-after-free Read in gfs2_invalidate_folio 19 24 211d 499d 0/3 auto-obsoleted due to no activity on 2026/06/08 21:36

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in list_empty include/linux/list.h:373 [inline]
BUG: KASAN: slab-use-after-free in gfs2_discard fs/gfs2/aops.c:622 [inline]
BUG: KASAN: slab-use-after-free in gfs2_invalidate_folio+0x42f/0xa30 fs/gfs2/aops.c:660
Read of size 8 at addr ffff88801d7231d8 by task syz-executor/5768

CPU: 1 PID: 5768 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 list_empty include/linux/list.h:373 [inline]
 gfs2_discard fs/gfs2/aops.c:622 [inline]
 gfs2_invalidate_folio+0x42f/0xa30 fs/gfs2/aops.c:660
 folio_invalidate mm/truncate.c:158 [inline]
 truncate_cleanup_folio+0x21f/0x5e0 mm/truncate.c:178
 truncate_inode_pages_range+0x275/0xea0 mm/truncate.c:392
 gfs2_evict_inode+0x42e/0x13c0 fs/gfs2/super.c:1536
 evict+0x4b7/0x8a0 fs/inode.c:705
 gfs2_evict_inodes fs/gfs2/ops_fstype.c:1770 [inline]
 gfs2_kill_sb+0x1fb/0x2e0 fs/gfs2/ops_fstype.c:1796
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x3d7/0x460 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9e8699f397
Code: a2 c7 05 5c 43 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffeb53aee58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9e86a3448b RCX: 00007f9e8699f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffeb53aef10
RBP: 00007ffeb53aef10 R08: 00007ffeb53aff10 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffeb53affa0
R13: 00007f9e86a3448b R14: 0000000000015022 R15: 00007ffeb53affe0
 </TASK>

Allocated by task 5845:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x17e/0x2c0 mm/slub.c:3519
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 gfs2_alloc_bufdata fs/gfs2/trans.c:168 [inline]
 gfs2_trans_add_data+0x1fb/0x5f0 fs/gfs2/trans.c:209
 gfs2_trans_add_databufs+0x15a/0x1c0 fs/gfs2/aops.c:57
 gfs2_iomap_put_folio+0x1be/0x410 fs/gfs2/bmap.c:994
 iomap_write_end+0x631/0xbc0 fs/iomap/buffered-io.c:897
 iomap_write_iter fs/iomap/buffered-io.c:963 [inline]
 iomap_file_buffered_write+0x751/0xda0 fs/iomap/buffered-io.c:1008
 gfs2_file_buffered_write+0x4c0/0x820 fs/gfs2/file.c:1060
 gfs2_file_write_iter+0x43d/0xe90 fs/gfs2/file.c:1158
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 3486:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 kmem_cache_free+0xf8/0x290 mm/slub.c:3852
 trans_drain fs/gfs2/log.c:1023 [inline]
 __gfs2_log_flush+0x18fd/0x24d0 fs/gfs2/log.c:1162
 gfs2_log_flush+0x34/0x50 fs/gfs2/log.c:1180
 gfs2_write_inode+0x1ec/0x370 fs/gfs2/super.c:457
 write_inode fs/fs-writeback.c:1534 [inline]
 __writeback_single_inode+0x720/0xee0 fs/fs-writeback.c:1751
 writeback_sb_inodes+0x813/0x1020 fs/fs-writeback.c:1977
 wb_writeback+0x45e/0xbe0 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x400/0xe60 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff88801d7231c0
 which belongs to the cache gfs2_bufdata of size 80
The buggy address is located 24 bytes inside of
 freed 80-byte region [ffff88801d7231c0, ffff88801d723210)

The buggy address belongs to the physical page:
page:ffffea000075c8c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d723
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888145edc500 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000240024 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 5845, tgid 5844 (syz.0.1), ts 85826138460, free_ts 85729927702
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x109/0x2c0 mm/slub.c:3519
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 gfs2_alloc_bufdata fs/gfs2/trans.c:168 [inline]
 gfs2_trans_add_meta+0x31b/0xc60 fs/gfs2/trans.c:251
 do_gfs2_set_flags fs/gfs2/file.c:265 [inline]
 gfs2_fileattr_set+0x6da/0x970 fs/gfs2/file.c:311
 vfs_fileattr_set+0x85d/0xb10 fs/ioctl.c:697
 ioctl_setflags fs/ioctl.c:729 [inline]
 do_vfs_ioctl+0x1442/0x1cc0 fs/ioctl.c:840
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x319/0x400 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x194/0x250 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa7/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 tomoyo_realpath_from_path+0xe6/0x5c0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x282/0x560 security/tomoyo/file.c:822
 security_file_truncate+0x62/0x90 security/security.c:2987
 handle_truncate fs/namei.c:3340 [inline]
 do_open fs/namei.c:3687 [inline]
 path_openat+0x29fe/0x3270 fs/namei.c:3844
 do_filp_open+0x1f2/0x430 fs/namei.c:3871

Memory state around the buggy address:
 ffff88801d723080: fb fb fb fb fb fb fb fb fc fc fc fc fa fb fb fb
 ffff88801d723100: fb fb fb fb fb fb fc fc fc fc fa fb fb fb fb fb
>ffff88801d723180: fb fb fb fb fc fc fc fc fa fb fb fb fb fb fb fb
                                                    ^
 ffff88801d723200: fb fb fc fc fc fc fa fb fb fb fb fb fb fb fb fb
 ffff88801d723280: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fc fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 00:09 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/09/11 19:36 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/08/31 11:12 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/08/31 11:06 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/08/31 10:55 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/08/31 10:32 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
2026/08/31 10:26 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gfs2_invalidate_folio
* Struck through repros no longer work on HEAD.