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BUG: KASAN: use-after-free in dx_insert_block fs/ext4/namei.c:1387 [inline]
BUG: KASAN: use-after-free in do_split+0x1a78/0x1f70 fs/ext4/namei.c:2080
Read of size 157024 at addr ffff88812af7c028 by task syz.1.173/1265

CPU: 0 PID: 1265 Comm: syz.1.173 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 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+0xf1/0x140 mm/kasan/report.c:444
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block fs/ext4/namei.c:1387 [inline]
 do_split+0x1a78/0x1f70 fs/ext4/namei.c:2080
 make_indexed_dir+0xe01/0x14a0 fs/ext4/namei.c:2392
 ext4_add_entry+0xc24/0xf40 fs/ext4/namei.c:2504
 __ext4_link+0x4d7/0x770 fs/ext4/namei.c:3536
 ext4_link+0x1de/0x270 fs/ext4/namei.c:3577
 vfs_link+0x636/0x7f0 fs/namei.c:4557
 do_linkat+0x1e7/0x730 fs/namei.c:4628
 __do_sys_link fs/namei.c:4662 [inline]
 __se_sys_link fs/namei.c:4660 [inline]
 __x64_sys_link+0x86/0x90 fs/namei.c:4660
 x64_sys_call+0x34d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:87
 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: 0033:0x7fa3584a7169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa357f19038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007fa3586bffa0 RCX: 00007fa3584a7169
RDX: 0000000000000000 RSI: 0000400000000bc0 RDI: 0000400000001240
RBP: 00007fa3585282a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa3586bffa0 R15: 00007ffdf26a1ab8
 </TASK>

The buggy address belongs to the page:
page:ffffea0004abdf00 refcount:3 mapcount:1 mapping:ffff888100480d98 index:0x1 pfn:0x12af7c
memcg:ffff888100251140
aops:def_blk_aops ino:700001
flags: 0x400000000032201e(referenced|uptodate|dirty|lru|private|mappedtodisk|unevictable|mlocked|zone=1)
raw: 400000000032201e ffff88810025aac0 ffffea000436ad08 ffff888100480d98
raw: 0000000000000001 ffff88810ce622a0 0000000300000000 ffff888100251140
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 767, ts 100651844466, free_ts 100578606419
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5795
 __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]
 __page_cache_alloc include/linux/pagemap.h:305 [inline]
 page_cache_ra_unbounded+0x2b2/0x980 mm/readahead.c:227
 do_page_cache_ra mm/readahead.c:280 [inline]
 force_page_cache_ra+0x3fd/0x460 mm/readahead.c:312
 page_cache_sync_ra+0x2ae/0x420 mm/readahead.c:590
 page_cache_sync_readahead include/linux/pagemap.h:831 [inline]
 filemap_get_pages mm/filemap.c:2568 [inline]
 filemap_read+0x63a/0x1f70 mm/filemap.c:2653
 generic_file_read_iter+0xac/0x400 mm/filemap.c:2813
 blkdev_read_iter+0x12f/0x160 block/fops.c:563
 call_read_iter include/linux/fs.h:2206 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x68b/0xbe0 fs/read_write.c:485
 ksys_read+0x140/0x240 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 x64_sys_call+0x96d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 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:1472 [inline]
 free_pcp_prepare mm/page_alloc.c:1544 [inline]
 free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534
 free_unref_page_list+0x134/0x9d0 mm/page_alloc.c:3671
 release_pages+0xfda/0x1030 mm/swap.c:1014
 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+0x175/0x300 mm/mmu_gather.c:338
 exit_mmap+0x40f/0x860 mm/mmap.c:3244
 __mmput+0x93/0x320 kernel/fork.c:1180
 mmput+0x50/0x150 kernel/fork.c:1203
 exit_mm kernel/exit.c:554 [inline]
 do_exit+0x9d2/0x27a0 kernel/exit.c:876
 do_group_exit+0x141/0x310 kernel/exit.c:1003
 __do_sys_exit_group kernel/exit.c:1014 [inline]
 __se_sys_exit_group kernel/exit.c:1012 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1012
 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 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:
 ffff88812af7cf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812af7cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88812af7d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88812af7d080: fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb
 ffff88812af7d100: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc
==================================================================
EXT4-fs error (device loop1): ext4_dx_csum_set:531: inode #2: comm syz.1.173: dir seems corrupt?  Run e2fsck -D.