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KASAN: slab-use-after-free Read in trylock_super

Status: auto-obsoleted due to no activity on 2023/07/01 04:40
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+e32313ff59595ad80aa3@syzkaller.appspotmail.com
First crash: 1059d, last: 1059d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: use-after-free Read in trylock_super 19 1 19d 19d 0/3 upstream: reported on 2026/02/05 06:22
android-5-15 KASAN: use-after-free Write in trylock_super vfs origin:lts 22 syz error 104 10d 1175d 0/2 premoderation: reported syz repro on 2022/12/07 03:02
android-54 KASAN: use-after-free Write in trylock_super 22 4 989d 1078d 0/2 auto-obsoleted due to no activity on 2023/09/19 19:51
linux-5.15 KASAN: use-after-free Read in trylock_super 19 1 424d 424d 0/3 auto-obsoleted due to no activity on 2025/04/06 15:01
android-5-10 KASAN: use-after-free Write in trylock_super vfs 22 syz inconclusive 106 56d 1182d 0/2 premoderation: reported syz repro on 2022/11/30 20:27

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __down_read_trylock kernel/locking/rwsem.c:1281 [inline]
BUG: KASAN: slab-use-after-free in down_read_trylock+0xac/0x3b0 kernel/locking/rwsem.c:1559
Read of size 8 at addr ffff88802b5e40d8 by task kworker/u4:5/1065

CPU: 1 PID: 1065 Comm: kworker/u4:5 Not tainted 6.3.0-rc4-syzkaller-00224-g00c7b5f4ddc5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:319 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:430
 kasan_report+0x176/0x1b0 mm/kasan/report.c:536
 __down_read_trylock kernel/locking/rwsem.c:1281 [inline]
 down_read_trylock+0xac/0x3b0 kernel/locking/rwsem.c:1559
 trylock_super+0x1f/0xf0 fs/super.c:414
 __writeback_inodes_wb+0x101/0x260 fs/fs-writeback.c:1953
 wb_writeback+0x46c/0xc70 fs/fs-writeback.c:2067
 wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
 wb_do_writeback fs/fs-writeback.c:2220 [inline]
 wb_workfn+0xbb5/0xff0 fs/fs-writeback.c:2248
 process_one_work+0x8a0/0x10e0 kernel/workqueue.c:2390
 worker_thread+0xa63/0x1210 kernel/workqueue.c:2537
 kthread+0x270/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>

Allocated by task 5135:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:196 [inline]
 __do_kmalloc_node mm/slab_common.c:967 [inline]
 __kmalloc+0xb9/0x230 mm/slab_common.c:980
 kmalloc include/linux/slab.h:584 [inline]
 tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x28d/0x700 security/tomoyo/file.c:822
 tomoyo_path_unlink+0xd0/0x110 security/tomoyo/tomoyo.c:161
 security_path_unlink+0xdb/0x130 security/security.c:1203
 do_unlinkat+0x3db/0x940 fs/namei.c:4313
 __do_sys_unlink fs/namei.c:4364 [inline]
 __se_sys_unlink fs/namei.c:4362 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4362
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5135:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:162 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook mm/slub.c:1807 [inline]
 slab_free mm/slub.c:3787 [inline]
 __kmem_cache_free+0x264/0x3c0 mm/slub.c:3800
 tomoyo_realpath_from_path+0x5a3/0x5e0 security/tomoyo/realpath.c:286
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x28d/0x700 security/tomoyo/file.c:822
 tomoyo_path_unlink+0xd0/0x110 security/tomoyo/tomoyo.c:161
 security_path_unlink+0xdb/0x130 security/security.c:1203
 do_unlinkat+0x3db/0x940 fs/namei.c:4313
 __do_sys_unlink fs/namei.c:4364 [inline]
 __se_sys_unlink fs/namei.c:4362 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4362
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb0/0xc0 mm/kasan/generic.c:491
 insert_work+0x54/0x3d0 kernel/workqueue.c:1361
 __queue_work+0xb37/0xf10 kernel/workqueue.c:1524
 queue_work_on+0x14f/0x250 kernel/workqueue.c:1552
 rcu_do_batch kernel/rcu/tree.c:2112 [inline]
 rcu_core+0xa4d/0x16f0 kernel/rcu/tree.c:2372
 __do_softirq+0x2ab/0x908 kernel/softirq.c:571

Second to last potentially related work creation:
 kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xb0/0xc0 mm/kasan/generic.c:491
 __call_rcu_common kernel/rcu/tree.c:2622 [inline]
 call_rcu+0x167/0xa70 kernel/rcu/tree.c:2736
 put_super fs/super.c:310 [inline]
 deactivate_locked_super+0xd8/0x110 fs/super.c:342
 cleanup_mnt+0x426/0x4c0 fs/namespace.c:1177
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88802b5e4000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 216 bytes inside of
 freed 4096-byte region [ffff88802b5e4000, ffff88802b5e5000)

The buggy address belongs to the physical page:
page:ffffea0000ad7800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b5e0
head:ffffea0000ad7800 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012442140 ffffea0000a2d800 dead000000000002
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5120, tgid 5120 (udevd), ts 409758051189, free_ts 409709006154
 prep_new_page mm/page_alloc.c:2553 [inline]
 get_page_from_freelist+0x3246/0x33c0 mm/page_alloc.c:4326
 __alloc_pages+0x255/0x670 mm/page_alloc.c:5592
 alloc_slab_page+0x6a/0x160 mm/slub.c:1851
 allocate_slab mm/slub.c:1998 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2051
 ___slab_alloc+0xa85/0x10a0 mm/slub.c:3193
 __slab_alloc mm/slub.c:3292 [inline]
 __slab_alloc_node mm/slub.c:3345 [inline]
 slab_alloc_node mm/slub.c:3442 [inline]
 __kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3491
 __do_kmalloc_node mm/slab_common.c:966 [inline]
 __kmalloc+0xa8/0x230 mm/slab_common.c:980
 kmalloc include/linux/slab.h:584 [inline]
 tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x28d/0x700 security/tomoyo/file.c:822
 tomoyo_path_unlink+0xd0/0x110 security/tomoyo/tomoyo.c:161
 security_path_unlink+0xdb/0x130 security/security.c:1203
 do_unlinkat+0x3db/0x940 fs/namei.c:4313
 __do_sys_unlink fs/namei.c:4364 [inline]
 __se_sys_unlink fs/namei.c:4362 [inline]
 __x64_sys_unlink+0x49/0x50 fs/namei.c:4362
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1454 [inline]
 free_pcp_prepare mm/page_alloc.c:1504 [inline]
 free_unref_page_prepare+0xe2f/0xe70 mm/page_alloc.c:3388
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:3483
 discard_slab mm/slub.c:2098 [inline]
 __unfreeze_partials+0x1b1/0x1f0 mm/slub.c:2637
 put_cpu_partial+0x116/0x180 mm/slub.c:2713
 qlist_free_all+0x22/0x60 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:186 [inline]
 slab_post_alloc_hook+0x68/0x3a0 mm/slab.h:769
 slab_alloc_node mm/slub.c:3452 [inline]
 slab_alloc mm/slub.c:3460 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3467 [inline]
 kmem_cache_alloc+0x11f/0x2e0 mm/slub.c:3476
 getname_flags+0xbc/0x4e0 fs/namei.c:140
 vfs_fstatat fs/stat.c:275 [inline]
 __do_sys_newfstatat fs/stat.c:446 [inline]
 __se_sys_newfstatat fs/stat.c:440 [inline]
 __x64_sys_newfstatat+0x12e/0x1d0 fs/stat.c:440
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88802b5e3f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802b5e4000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802b5e4080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88802b5e4100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802b5e4180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/04/02 04:40 upstream 00c7b5f4ddc5 f325deb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in trylock_super
* Struck through repros no longer work on HEAD.