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KASAN: use-after-free Read in ocfs2_get_system_file_inode

Status: upstream: reported C repro on 2025/08/25 08:51
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+900962ac9bf1860033f2@syzkaller.appspotmail.com
First crash: 4d20h, last: 3d17h
Cause bisection: introduced by (bisect log) :
commit bd1261b16d9131d79723d982d54295e7f309797a
Author: Heming Zhao <heming.zhao@suse.com>
Date: Mon Apr 14 06:01:23 2025 +0000

  ocfs2: fix the issue with discontiguous allocation in the global_bitmap

Crash: KASAN: slab-use-after-free Read in ocfs2_get_system_file_inode (log)
Repro: syz .config
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ocfs2?] KASAN: use-after-free Read in ocfs2_get_system_file_inode 0 (2) 2025/08/26 07:15
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-out-of-bounds Read in ocfs2_get_system_file_inode ocfs2 17 1 191d 187d 0/29 auto-obsoleted due to no activity on 2025/05/28 15:56
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/08/26 07:15 24m dmantipov@yandex.ru patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fab1beda7597fac1cecc01707d55eadb6bbe773c OK log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ocfs2_get_system_file_inode+0x17c/0x650 fs/ocfs2/sysfile.c:102
Read of size 8 at addr ffff0000dea2ae10 by task syz-executor/6666

CPU: 1 UID: 0 PID: 6666 Comm: syz-executor Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 print_address_description+0xa8/0x238 mm/kasan/report.c:378
 print_report+0x68/0x84 mm/kasan/report.c:482
 kasan_report+0xb0/0x110 mm/kasan/report.c:595
 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381
 ocfs2_get_system_file_inode+0x17c/0x650 fs/ocfs2/sysfile.c:102
 ocfs2_remove_inode fs/ocfs2/inode.c:723 [inline]
 ocfs2_wipe_inode fs/ocfs2/inode.c:894 [inline]
 ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
 ocfs2_evict_inode+0x12e8/0x3bf8 fs/ocfs2/inode.c:1292
 evict+0x414/0x928 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput+0x6e4/0x83c fs/inode.c:1923
 d_delete_notify include/linux/fsnotify.h:377 [inline]
 vfs_rmdir+0x358/0x464 fs/namei.c:4474
 do_rmdir+0x214/0x4c4 fs/namei.c:4516
 __do_sys_unlinkat fs/namei.c:4690 [inline]
 __se_sys_unlinkat fs/namei.c:4684 [inline]
 __arm64_sys_unlinkat+0xc8/0xf8 fs/namei.c:4684
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Allocated by task 6734:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:562
 unpoison_slab_object mm/kasan/common.c:330 [inline]
 __kasan_slab_alloc+0x70/0x88 mm/kasan/common.c:356
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_noprof+0x238/0x3e8 mm/slub.c:4236
 anon_vma_chain_alloc mm/rmap.c:142 [inline]
 __anon_vma_prepare+0xc4/0x3fc mm/rmap.c:195
 __vmf_anon_prepare mm/memory.c:3506 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5050 [inline]
 do_pte_missing mm/memory.c:4232 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0x4308/0x4d34 mm/memory.c:6364
 do_page_fault+0x410/0x13cc arch/arm64/mm/fault.c:653
 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:789
 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:929
 el0_da+0x64/0x164 arch/arm64/kernel/entry-common.c:697
 el0t_64_sync_handler+0x90/0x12c arch/arm64/kernel/entry-common.c:901
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

Freed by task 6734:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x74/0x98 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kmem_cache_free+0x184/0x550 mm/slub.c:4782
 anon_vma_chain_free mm/rmap.c:147 [inline]
 unlink_anon_vmas+0x48c/0x520 mm/rmap.c:447
 free_pgtables+0x3c8/0x5d4 mm/memory.c:413
 exit_mmap+0x350/0xabc mm/mmap.c:1291
 __mmput+0xec/0x3f4 kernel/fork.c:1130
 mmput+0x70/0xac kernel/fork.c:1152
 exit_mm+0x13c/0x200 kernel/exit.c:582
 do_exit+0x4bc/0x1a14 kernel/exit.c:949
 do_group_exit+0x194/0x22c kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 pid_child_should_wake+0x0/0x1dc kernel/exit.c:1111
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

The buggy address belongs to the object at ffff0000dea2ae00
 which belongs to the cache anon_vma_chain of size 80
The buggy address is located 16 bytes inside of
 freed 80-byte region [ffff0000dea2ae00, ffff0000dea2ae50)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11ea2a
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000000 ffff0000c18ad280 fffffdffc37a8980 0000000000000002
raw: 0000000000000000 0000000000240024 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000dea2ad00: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fc fc
 ffff0000dea2ad80: fc fc fa fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff0000dea2ae00: fa fb fb fb fb fb fb fb fb fb fc fc fc fc fa fb
                         ^
 ffff0000dea2ae80: fb fb fb fb fb fb fb fb fc fc fc fc fa fb fb fb
 ffff0000dea2af00: fb fb fb fb fb fb fc fc fc fc fa fb fb fb fb fb
==================================================================
Unable to handle kernel paging request at virtual address fbd5200000000030
KASAN: maybe wild-memory-access in range [0xdead000000000180-0xdead000000000187]
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[fbd5200000000030] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6666 Comm: syz-executor Tainted: G    B               6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
pc : do_raw_spin_lock+0x84/0x2cc kernel/locking/spinlock_debug.c:115
lr : __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
lr : _raw_spin_lock+0x50/0x60 kernel/locking/spinlock.c:154
sp : ffff8000a28a7040
x29: ffff8000a28a70c0 x28: 0000000000000000 x27: ffff8000a28a7180
x26: dfff800000000000 x25: ffff700014514e30 x24: dfff800000000000
x23: 0000000000000800 x22: ffff0000dea2ae10 x21: ffff0000c68f0000
x20: dead000000000184 x19: dead000000000180 x18: 00000000ffffffff
x17: 3d3d3d3d3d3d3d3d x16: ffff8000805354d8 x15: 0000000000000001
x14: 1ffff0001260d8fc x13: 0000000000000000 x12: 0000000000000000
x11: 1ffff00014514e0c x10: ffff80008efad53b x9 : f3f3f304f1f1f1f1
x8 : 1bd5a00000000030 x7 : 0000000000000001 x6 : ffff800080dd7c18
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : ffff80008b6577c0 x0 : dead000000000180
Call trace:
 debug_spin_lock_before kernel/locking/spinlock_debug.c:-1 [inline] (P)
 do_raw_spin_lock+0x84/0x2cc kernel/locking/spinlock_debug.c:115 (P)
 __raw_spin_lock include/linux/spinlock_api_smp.h:134 [inline]
 _raw_spin_lock+0x50/0x60 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 igrab+0x20/0xd8 fs/inode.c:1540
 ocfs2_get_system_file_inode+0x188/0x650 fs/ocfs2/sysfile.c:104
 ocfs2_remove_inode fs/ocfs2/inode.c:723 [inline]
 ocfs2_wipe_inode fs/ocfs2/inode.c:894 [inline]
 ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
 ocfs2_evict_inode+0x12e8/0x3bf8 fs/ocfs2/inode.c:1292
 evict+0x414/0x928 fs/inode.c:810
 iput_final fs/inode.c:1897 [inline]
 iput+0x6e4/0x83c fs/inode.c:1923
 d_delete_notify include/linux/fsnotify.h:377 [inline]
 vfs_rmdir+0x358/0x464 fs/namei.c:4474
 do_rmdir+0x214/0x4c4 fs/namei.c:4516
 __do_sys_unlinkat fs/namei.c:4690 [inline]
 __se_sys_unlinkat fs/namei.c:4684 [inline]
 __arm64_sys_unlinkat+0xc8/0xf8 fs/namei.c:4684
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
Code: aa0003f3 f9000feb f2fe7e69 f8386969 (38f86908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa0003f3 	mov	x19, x0
   4:	f9000feb 	str	x11, [sp, #24]
   8:	f2fe7e69 	movk	x9, #0xf3f3, lsl #48
   c:	f8386969 	str	x9, [x11, x24]
* 10:	38f86908 	ldrsb	w8, [x8, x24] <-- trapping instruction

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/23 01:42 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8f5ae30d69d7 bf27483f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ocfs2_get_system_file_inode
2025/08/23 00:08 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8f5ae30d69d7 bf27483f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ocfs2_get_system_file_inode
2025/08/22 23:20 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8f5ae30d69d7 bf27483f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-upstream-gce-arm64 KASAN: slab-use-after-free Read in ocfs2_get_system_file_inode
2025/08/24 01:17 upstream 8d245acc1e88 bf27483f .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-upstream-fs KASAN: slab-use-after-free Read in ocfs2_get_system_file_inode
2025/08/22 22:32 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 8f5ae30d69d7 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: use-after-free Read in ocfs2_get_system_file_inode
* Struck through repros no longer work on HEAD.