syzbot


KASAN: use-after-free Read in gfs2_invalidate_folio

Status: upstream: reported on 2025/05/16 19:32
Reported-by: syzbot+ad31dfa0b430a4497f2a@syzkaller.appspotmail.com
First crash: 108d, last: 14d
Similar bugs (2)
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 2 29d 29d 0/2 upstream: reported on 2025/08/04 00:39
upstream KASAN: slab-use-after-free Read in gfs2_invalidate_folio gfs2 19 C error 63 5h30m 508d 0/29 upstream: reported C repro on 2024/04/11 16:17

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in list_empty include/linux/list.h:292 [inline]
BUG: KASAN: use-after-free in gfs2_discard fs/gfs2/aops.c:618 [inline]
BUG: KASAN: use-after-free in gfs2_invalidate_folio+0x455/0xa70 fs/gfs2/aops.c:656
Read of size 8 at addr ffff888063e50088 by task syz-executor/4275

CPU: 0 PID: 4275 Comm: syz-executor Not tainted 6.1.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 list_empty include/linux/list.h:292 [inline]
 gfs2_discard fs/gfs2/aops.c:618 [inline]
 gfs2_invalidate_folio+0x455/0xa70 fs/gfs2/aops.c:656
 folio_invalidate mm/truncate.c:158 [inline]
 truncate_cleanup_folio+0x218/0x5e0 mm/truncate.c:178
 truncate_inode_pages_range+0x237/0xff0 mm/truncate.c:368
 gfs2_evict_inode+0xab5/0x1170 fs/gfs2/super.c:1511
 evict+0x485/0x870 fs/inode.c:705
 dispose_list fs/inode.c:738 [inline]
 evict_inodes+0x604/0x690 fs/inode.c:792
 generic_shutdown_super+0x93/0x340 fs/super.c:480
 kill_block_super+0x7c/0xe0 fs/super.c:1470
 deactivate_locked_super+0x93/0xf0 fs/super.c:332
 cleanup_mnt+0x463/0x4f0 fs/namespace.c:1182
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x93e/0x2400 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7d8598ebe9
Code: Unable to access opcode bytes at 0x7f7d8598ebbf.
RSP: 002b:00007ffcb3e69628 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f7d85a11c2a RCX: 00007f7d8598ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000005 R08: 00007ffcb3e673c7 R09: 00007ffcb3e6a880
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcb3e6a880
R13: 00007f7d85a11c05 R14: 000000000001e1af R15: 00007ffcb3e6a8c0
 </TASK>

Allocated by task 5464:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3398 [inline]
 slab_alloc mm/slub.c:3406 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
 kmem_cache_alloc+0x123/0x2f0 mm/slub.c:3422
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 gfs2_alloc_bufdata fs/gfs2/trans.c:168 [inline]
 gfs2_trans_add_data+0x1fb/0x610 fs/gfs2/trans.c:209
 gfs2_page_add_databufs+0x1eb/0x270 fs/gfs2/aops.c:57
 gfs2_iomap_page_done+0xe0/0x180 fs/gfs2/bmap.c:978
 iomap_write_end+0x762/0xda0 fs/iomap/buffered-io.c:739
 iomap_write_iter fs/iomap/buffered-io.c:802 [inline]
 iomap_file_buffered_write+0x4ce/0x880 fs/iomap/buffered-io.c:847
 gfs2_file_buffered_write+0x4fe/0x880 fs/gfs2/file.c:1057
 gfs2_file_write_iter+0x42c/0xdf0 fs/gfs2/file.c:1158
 call_write_iter include/linux/fs.h:2265 [inline]
 aio_write+0x50e/0x720 fs/aio.c:1615
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0x6aa/0x1300 fs/aio.c:2034
 __do_sys_io_submit fs/aio.c:2093 [inline]
 __se_sys_io_submit+0x190/0x300 fs/aio.c:2063
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 5464:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 kmem_cache_free+0xf7/0x290 mm/slub.c:3683
 trans_drain fs/gfs2/log.c:1023 [inline]
 gfs2_log_flush+0x1902/0x24e0 fs/gfs2/log.c:1161
 gfs2_jdata_writepages+0xf5/0x150 fs/gfs2/aops.c:392
 do_writepages+0x3b7/0x610 mm/page-writeback.c:2491
 filemap_fdatawrite_wbc+0x11e/0x180 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 filemap_fdatawrite_range+0xca/0x120 mm/filemap.c:439
 gfs2_fsync+0xdb/0x340 fs/gfs2/file.c:747
 generic_write_sync include/linux/fs.h:2962 [inline]
 gfs2_file_write_iter+0xc60/0xdf0 fs/gfs2/file.c:1160
 call_write_iter include/linux/fs.h:2265 [inline]
 aio_write+0x50e/0x720 fs/aio.c:1615
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0x6aa/0x1300 fs/aio.c:2034
 __do_sys_io_submit fs/aio.c:2093 [inline]
 __se_sys_io_submit+0x190/0x300 fs/aio.c:2063
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888063e50070
 which belongs to the cache gfs2_bufdata of size 80
The buggy address is located 24 bytes inside of
 80-byte region [ffff888063e50070, ffff888063e500c0)

The buggy address belongs to the physical page:
page:ffffea00018f9400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x63e50
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff88801bbee140
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 5464, tgid 5463 (syz.3.161), ts 123114342886, free_ts 122726757349
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 alloc_slab_page+0x5d/0x160 mm/slub.c:1794
 allocate_slab mm/slub.c:1939 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1992
 ___slab_alloc+0xbc6/0x1220 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 slab_alloc mm/slub.c:3406 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
 kmem_cache_alloc+0x1b7/0x2f0 mm/slub.c:3422
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 gfs2_alloc_bufdata fs/gfs2/trans.c:168 [inline]
 gfs2_trans_add_meta+0x34e/0xc60 fs/gfs2/trans.c:250
 init_dinode+0x97/0xa30 fs/gfs2/inode.c:479
 gfs2_create_inode+0xfb1/0x1400 fs/gfs2/inode.c:747
 gfs2_atomic_open+0xce/0x210 fs/gfs2/inode.c:1293
 atomic_open fs/namei.c:3345 [inline]
 lookup_open fs/namei.c:3453 [inline]
 open_last_lookups fs/namei.c:3550 [inline]
 path_openat+0xe20/0x2e70 fs/namei.c:3780
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
 do_sys_openat2+0x142/0x490 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_creat fs/open.c:1412 [inline]
 __se_sys_creat fs/open.c:1406 [inline]
 __x64_sys_creat+0x8c/0xb0 fs/open.c:1406
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3525
 release_pages+0x1f92/0x2200 mm/swap.c:1035
 __pagevec_release+0x6d/0xe0 mm/swap.c:1055
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 truncate_inode_pages_range+0x2f6/0xff0 mm/truncate.c:372
 gfs2_find_jhead+0xc5d/0xd00 fs/gfs2/lops.c:602
 gfs2_make_fs_rw+0x1f4/0x560 fs/gfs2/super.c:140
 gfs2_fill_super+0x1888/0x1f80 fs/gfs2/ops_fstype.c:1271
 get_tree_bdev+0x3f1/0x610 fs/super.c:1366
 gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1327
 vfs_get_tree+0x88/0x270 fs/super.c:1573
 do_new_mount+0x24a/0xa40 fs/namespace.c:3063
 do_mount fs/namespace.c:3406 [inline]
 __do_sys_mount fs/namespace.c:3614 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3591
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888063e4ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888063e50000: fa fb fb fb fb fb fb fb fb fb fc fc fc fc fa fb
>ffff888063e50080: fb fb fb fb fb fb fb fb fc fc fc fc fa fb fb fb
                      ^
 ffff888063e50100: fb fb fb fb fb fb fc fc fc fc fa fb fb fb fb fb
 ffff888063e50180: fb fb fb fb fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/18 14:57 linux-6.1.y 0bc96de781b4 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in gfs2_invalidate_folio
2025/08/18 00:25 linux-6.1.y 0bc96de781b4 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in gfs2_invalidate_folio
2025/08/18 00:21 linux-6.1.y 0bc96de781b4 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in gfs2_invalidate_folio
2025/08/01 21:38 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in gfs2_invalidate_folio
2025/05/16 19:32 linux-6.1.y 02b72ccb5f9d cfde8269 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gfs2_invalidate_folio
* Struck through repros no longer work on HEAD.