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KASAN: use-after-free Read in do_sync

Status: upstream: reported on 2025/11/09 04:56
Reported-by: syzbot+f99039e908a5ef9baaf2@syzkaller.appspotmail.com
First crash: 37d, last: 20d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: use-after-free Read in do_sync origin:upstream 19 C 12 7h20m 40d 0/3 upstream: reported C repro on 2025/11/05 15:12
upstream KASAN: slab-use-after-free Read in do_sync gfs2 19 2 163d 184d 0/29 auto-obsoleted due to no activity on 2025/10/04 08:28
linux-5.15 BUG: unable to handle kernel paging request in do_sync 8 3 203d 245d 0/3 auto-obsoleted due to no activity on 2025/09/03 20:25

Sample crash report:
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
==================================================================
BUG: KASAN: use-after-free in __up_write kernel/locking/rwsem.c:1344 [inline]
BUG: KASAN: use-after-free in up_write+0x67/0x420 kernel/locking/rwsem.c:1604
Read of size 8 at addr ffff888060de6700 by task gfs2_quotad/5384

CPU: 0 PID: 5384 Comm: gfs2_quotad Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 __up_write kernel/locking/rwsem.c:1344 [inline]
 up_write+0x67/0x420 kernel/locking/rwsem.c:1604
 inode_unlock include/linux/fs.h:792 [inline]
 do_sync+0x928/0xc00 fs/gfs2/quota.c:984
 gfs2_quota_sync+0x32c/0x6f0 fs/gfs2/quota.c:1329
 quotad_check_timeo fs/gfs2/quota.c:1519 [inline]
 gfs2_quotad+0x3f6/0x880 fs/gfs2/quota.c:1586
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 5360:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x9c/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 gfs2_alloc_inode+0x45/0x110 fs/gfs2/super.c:1447
 alloc_inode fs/inode.c:261 [inline]
 iget5_locked+0x9e/0x250 fs/inode.c:1263
 gfs2_iget fs/gfs2/inode.c:64 [inline]
 gfs2_inode_lookup+0xe5/0xd00 fs/gfs2/inode.c:140
 gfs2_dir_search+0x165/0x220 fs/gfs2/dir.c:1665
 gfs2_lookupi+0x45c/0x5e0 fs/gfs2/inode.c:332
 gfs2_lookup_simple+0xa3/0xf0 fs/gfs2/inode.c:273
 init_inodes+0x180/0x320 fs/gfs2/ops_fstype.c:906
 gfs2_fill_super+0x1701/0x1f50 fs/gfs2/ops_fstype.c:1249
 get_tree_bdev+0x3f1/0x610 fs/super.c:1325
 gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1332
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 14:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 rcu_do_batch kernel/rcu/tree.c:2523 [inline]
 rcu_core+0x962/0x15d0 kernel/rcu/tree.c:2763
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 run_ksoftirqd+0x98/0xf0 kernel/softirq.c:943
 smpboot_thread_fn+0x4f6/0x970 kernel/smpboot.c:164
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:3011 [inline]
 call_rcu+0x182/0x930 kernel/rcu/tree.c:3091
 destroy_inode fs/inode.c:316 [inline]
 evict+0x7da/0x870 fs/inode.c:662
 gfs2_put_super+0x2fe/0x7d0 fs/gfs2/super.c:603
 generic_shutdown_super+0x130/0x300 fs/super.c:475
 kill_block_super+0x7c/0xe0 fs/super.c:1427
 deactivate_locked_super+0x93/0xf0 fs/super.c:335
 cleanup_mnt+0x418/0x4d0 fs/namespace.c:1148
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888060de65b8
 which belongs to the cache gfs2_inode of size 1608
The buggy address is located 328 bytes inside of
 1608-byte region [ffff888060de65b8, ffff888060de6c00)
The buggy address belongs to the page:
page:ffffea0001837800 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888060de1458 pfn:0x60de0
head:ffffea0001837800 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff88805f5b6401
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff88801df20000
raw: ffff888060de1458 000000008012000b 00000001ffffffff ffff88805f5b6401
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0x1d20d0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 4695, ts 87559872685, free_ts 77708021406
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5487
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x195/0x290 mm/slub.c:3238
 gfs2_alloc_inode+0x45/0x110 fs/gfs2/super.c:1447
 alloc_inode fs/inode.c:261 [inline]
 iget5_locked+0x9e/0x250 fs/inode.c:1263
 gfs2_iget fs/gfs2/inode.c:64 [inline]
 gfs2_inode_lookup+0xe5/0xd00 fs/gfs2/inode.c:140
 gfs2_lookup_root fs/gfs2/ops_fstype.c:465 [inline]
 init_sb+0xa49/0x1330 fs/gfs2/ops_fstype.c:532
 gfs2_fill_super+0x13fb/0x1f50 fs/gfs2/ops_fstype.c:1216
 get_tree_bdev+0x3f1/0x610 fs/super.c:1325
 gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1332
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x94/0x280 mm/page_alloc.c:3396
 free_slab mm/slub.c:2020 [inline]
 discard_slab mm/slub.c:2026 [inline]
 __unfreeze_partials+0x1a5/0x200 mm/slub.c:2512
 put_cpu_partial+0x12d/0x190 mm/slub.c:2592
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 __kmalloc+0x127/0x330 mm/slub.c:4408
 kmalloc include/linux/slab.h:612 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x27e/0x540 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x5cd/0x610 security/tomoyo/realpath.c:288
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x1cd/0x510 security/tomoyo/file.c:822
 security_inode_getattr+0xcf/0x120 security/security.c:1348
 vfs_getattr+0x26/0x3a0 fs/stat.c:157
 vfs_fstat fs/stat.c:182 [inline]
 __do_sys_newfstat fs/stat.c:421 [inline]
 __se_sys_newfstat fs/stat.c:418 [inline]
 __x64_sys_newfstat+0x104/0x1d0 fs/stat.c:418
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80

Memory state around the buggy address:
 ffff888060de6600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888060de6680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888060de6700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888060de6780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888060de6800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/09 04:55 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in do_sync
2025/11/25 19:11 linux-5.15.y cc5ec8769306 64219f15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in do_sync
* Struck through repros no longer work on HEAD.