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BUG: KASAN: use-after-free in ext4_get_inode_usage+0x39c/0x520 fs/ext4/xattr.c:821
Read of size 4 at addr ffff8881249f2070 by task syz.2.23/518

CPU: 1 PID: 518 Comm: syz.2.23 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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+0x39c/0x520 fs/ext4/xattr.c:821
 __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: 0033:0x7f2b94dd2e59
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:00007f2b94c35028 EFLAGS: 00000246 ORIG_RAX: 000000000000005e
RAX: ffffffffffffffda RBX: 00007f2b9504bfa0 RCX: 00007f2b94dd2e59
RDX: 000000000000ee01 RSI: 0000000000000000 RDI: 00002000000006c0
RBP: 00007f2b94e68e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b9504c038 R14: 00007f2b9504bfa0 R15: 00007ffcb6543618
 </TASK>

The buggy address belongs to the page:
page:ffffea0004927c80 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x1 pfn:0x1249f2
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea000490e808 ffffea000492e088 0000000000000000
raw: 0000000000000001 0000000000000001 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 416, ts 39165963811, free_ts 39563960411
 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
 vm_area_alloc_pages mm/vmalloc.c:-1 [inline]
 __vmalloc_area_node mm/vmalloc.c:2981 [inline]
 __vmalloc_node_range+0x507/0xad0 mm/vmalloc.c:3147
 vmalloc_user+0x73/0x80 mm/vmalloc.c:3298
 kcov_mmap+0x2b/0x130 kernel/kcov.c:474
 call_mmap include/linux/fs.h:2217 [inline]
 mmap_file+0x60/0xb0 mm/util.c:1099
 __mmap_region mm/mmap.c:1808 [inline]
 mmap_region+0xe42/0x1700 mm/mmap.c:2959
 do_mmap+0x812/0xf10 mm/mmap.c:1598
 vm_mmap_pgoff+0x1d6/0x410 mm/util.c:555
 ksys_mmap_pgoff+0x161/0x1d0 mm/mmap.c:1647
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
 x64_sys_call+0x83/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:10
 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
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+0xae/0x540 mm/page_alloc.c:3618
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x6c/0x100 mm/page_alloc.c:5900
 __vunmap+0x801/0x980 mm/vmalloc.c:2660
 __vfree mm/vmalloc.c:2709 [inline]
 vfree+0x8b/0xc0 mm/vmalloc.c:2740
 kcov_put kernel/kcov.c:417 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:519
 __fput+0x22b/0x900 fs/file_table.c:311
 ____fput+0x15/0x20 fs/file_table.c:339
 task_work_run+0x127/0x190 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xb70/0x29a0 kernel/exit.c:896
 do_group_exit+0x149/0x310 kernel/exit.c:1010
 get_signal+0x64f/0x1430 kernel/signal.c:2916
 arch_do_signal_or_restart+0xe2/0x1100 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307

Memory state around the buggy address:
 ffff8881249f1f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881249f1f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881249f2000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff8881249f2080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881249f2100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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