KASAN: slab-out-of-bounds Read in ext4_get_inode_usage

Status: upstream: reported C repro on 2026/05/16 23:51
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+45e23e06cf4d881e85a5@syzkaller.appspotmail.com
First crash: 69d, last: 14d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/05/17 lts (merge base) de8dfb3f0278 C [report] lost connection to test machine
2026/05/17 upstream (ToT) 6916d5703ddf C [report] lost connection to test machine
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: use-after-free Read in ext4_get_inode_usage 19 C 43 15d 70d 0/2 upstream: reported C repro on 2026/05/15 18:41
linux-5.15 KASAN: use-after-free Read in ext4_get_inode_usage origin:upstream 19 C 2 19d 69d 0/3 upstream: reported C repro on 2026/05/17 01:53
android-6-1 KASAN: use-after-free Read in ext4_get_inode_usage 19 C 12 5d18h 15d 0/2 upstream: reported C repro on 2026/07/09 15:06
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2026/06/04 12:11 13m retest repro android13-5.15-lts log
2026/06/04 12:11 15m retest repro android13-5.15-lts log
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/06/16 13:57 2h59m bisect fix android13-5.15-lts OK (0) job log log

Sample crash report:
EXT4-fs (loop2): mounted filesystem without journal. Opts: ,errors=continue. Quota mode: writeback.
EXT4-fs error (device loop2): xattr_find_entry:297: inode #15: comm syz.2.17: corrupted xattr entries
==================================================================
BUG: KASAN: use-after-free in ext4_get_inode_usage+0x371/0x520 fs/ext4/xattr.c:823
Read of size 4 at addr ffff888127a44000 by task syz.2.17/371

CPU: 0 PID: 371 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x10f/0x150 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_get_inode_usage+0x371/0x520 fs/ext4/xattr.c:823
 __dquot_transfer+0x192/0x22d0 fs/quota/dquot.c:2037
 dquot_transfer+0x2f3/0x470 fs/quota/dquot.c:2189
 ext4_setattr+0x746/0x1b10 fs/ext4/inode.c:5508
 notify_change+0xc30/0xf40 fs/attr.c:505
 chown_common+0x4b4/0x680 fs/open.c:681
 do_fchownat+0x147/0x240 fs/open.c:712
 __do_sys_lchown fs/open.c:737 [inline]
 __se_sys_lchown fs/open.c:735 [inline]
 __x64_sys_lchown+0x85/0x90 fs/open.c:735
 x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:95
 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
RIP: 0033:0x7ffa015f4e59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd8ff851a8 EFLAGS: 00000246 ORIG_RAX: 000000000000005e
RAX: ffffffffffffffda RBX: 00007ffa0187cfa0 RCX: 00007ffa015f4e59
RDX: 0000000000000000 RSI: 00000000000000ff RDI: 00002000000004c0
RBP: 00007ffa0168ae6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffa0187cfac R14: 00007ffa0187cfa0 R15: 00007ffa0187cfa0
 </TASK>

The buggy address belongs to the page:
page:ffffea00049e9100 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x127a44
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004a06f08 ffffea0004a06b48 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 307, ts 25192760476, free_ts 25194555890
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
 __alloc_pages_node include/linux/gfp.h:595 [inline]
 alloc_pages_node include/linux/gfp.h:609 [inline]
 alloc_pages include/linux/gfp.h:622 [inline]
 do_anonymous_page mm/memory.c:4072 [inline]
 handle_pte_fault+0xee5/0x2770 mm/memory.c:4921
 __handle_mm_fault mm/memory.c:-1 [inline]
 do_handle_mm_fault+0x1b3b/0x1e30 mm/memory.c:5345
 handle_mm_fault include/linux/mm.h:1847 [inline]
 do_user_addr_fault+0x808/0x11c0 arch/x86/mm/fault.c:1416
 handle_page_fault arch/x86/mm/fault.c:1507 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1560
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:606
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1474 [inline]
 free_pcp_prepare mm/page_alloc.c:1546 [inline]
 free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536
 free_unref_page_list+0x138/0x9e0 mm/page_alloc.c:3673
 release_pages+0x1264/0x12c0 mm/swap.c:1015
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:320
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x17e/0x310 mm/mmu_gather.c:338
 unmap_region+0x344/0x3b0 mm/mmap.c:2692
 __do_munmap+0xa99/0x1090 mm/mmap.c:2925
 __vm_munmap+0x14e/0x280 mm/mmap.c:2978
 __do_sys_munmap mm/mmap.c:3004 [inline]
 __se_sys_munmap mm/mmap.c:3000 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:3000
 x64_sys_call+0xc9/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12
 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

Memory state around the buggy address:
 ffff888127a43f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888127a43f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888127a44000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888127a44080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888127a44100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/10 20:56 android13-5.15-lts 0a85a2bd13c2 99e64375 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/07/10 20:26 android13-5.15-lts 0a85a2bd13c2 99e64375 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 22:57 android13-5.15-lts c85054db4618 7ff32d8b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 07:57 android13-5.15-lts c85054db4618 cfa969bf .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 03:49 android13-5.15-lts c85054db4618 302586aa .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 01:51 android13-5.15-lts c85054db4618 302586aa .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/05/17 00:03 android13-5.15-lts 7f4b368e0410 de5aae85 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/05/16 23:43 android13-5.15-lts 7f4b368e0410 de5aae85 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 04:24 android13-5.15-lts c85054db4618 302586aa .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/06/25 02:12 android13-5.15-lts c85054db4618 302586aa .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-15 KASAN: use-after-free Read in ext4_get_inode_usage
2026/05/16 22:29 android13-5.15-lts 7f4b368e0410 de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 KASAN: slab-out-of-bounds Read in ext4_get_inode_usage
* Struck through repros no longer work on HEAD.