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BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2602 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x31b1/0x4490 fs/ext4/extents.c:2940
Read of size 4 at addr ffff8880599fec18 by task syz-executor/4365

CPU: 0 PID: 4365 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 ext4_ext_rm_leaf fs/ext4/extents.c:2602 [inline]
 ext4_ext_remove_space+0x31b1/0x4490 fs/ext4/extents.c:2940
 ext4_ext_truncate+0x211/0x370 fs/ext4/extents.c:4470
 ext4_truncate+0xa0b/0x1230 fs/ext4/inode.c:4295
 ext4_evict_inode+0xb35/0x1100 fs/ext4/inode.c:286
 evict+0x485/0x870 fs/inode.c:705
 do_unlinkat+0x377/0x560 fs/namei.c:4405
 __do_sys_unlink fs/namei.c:4446 [inline]
 __se_sys_unlink fs/namei.c:4444 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f696838ecf7
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffe4289d68 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f696838ecf7
RDX: 00007fffe4289d90 RSI: 00007fffe4289e20 RDI: 00007fffe4289e20
RBP: 00007fffe4289e20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fffe428af10
R13: 00007f6968413d7d R14: 0000000000014c2b R15: 00007fffe428bfe0
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001667f80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x599fe
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 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 0x8(__GFP_MOVABLE), pid 1, tgid 1 (swapper/0), ts 18525378391, free_ts 19406995812
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 split_map_pages+0x277/0x4c0 mm/compaction.c:97
 isolate_freepages_range+0x3dd/0x430 mm/compaction.c:735
 alloc_contig_range+0x5ae/0x850 mm/page_alloc.c:9449
 __alloc_contig_pages mm/page_alloc.c:9472 [inline]
 alloc_contig_pages+0x396/0x490 mm/page_alloc.c:9552
 debug_vm_pgtable_alloc_huge_page+0xbf/0x10f mm/debug_vm_pgtable.c:1103
 init_args+0xb94/0xeda mm/debug_vm_pgtable.c:1226
 debug_vm_pgtable+0x56/0x37e mm/debug_vm_pgtable.c:1264
 do_one_initcall+0x214/0x7a0 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x3fa/0x5ac init/main.c:1638
 kernel_init+0x19/0x1b0 init/main.c:1526
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3479
 free_contig_range+0x9d/0x150 mm/page_alloc.c:9574
 destroy_args+0x100/0xa31 mm/debug_vm_pgtable.c:1031
 debug_vm_pgtable+0x32a/0x37e mm/debug_vm_pgtable.c:1359
 do_one_initcall+0x214/0x7a0 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x3fa/0x5ac init/main.c:1638
 kernel_init+0x19/0x1b0 init/main.c:1526
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff8880599feb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880599feb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880599fec00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff8880599fec80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880599fed00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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