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BUG: KASAN: use-after-free in ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2119
Write of size 251 at addr ffff888052dc0f14 by task syz.0.0/5312

CPU: 0 UID: 0 PID: 5312 Comm: syz.0.0 Not tainted 6.13.0-rc7-syzkaller-00209-g9528d418de4d #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2119
 add_dirent_to_buf+0x3d9/0x750 fs/ext4/namei.c:2164
 make_indexed_dir+0xf98/0x1600 fs/ext4/namei.c:2361
 ext4_add_entry+0xcf7/0xfa0 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0x920/0xb50 fs/ext4/namei.c:3438
 vfs_symlink+0x137/0x2e0 fs/namei.c:4669
 do_symlinkat+0x222/0x3a0 fs/namei.c:4695
 __do_sys_symlink fs/namei.c:4716 [inline]
 __se_sys_symlink fs/namei.c:4714 [inline]
 __x64_sys_symlink+0x7a/0x90 fs/namei.c:4714
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd27b785d29
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:00007fd27c68c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007fd27b975fa0 RCX: 00007fd27b785d29
RDX: 0000000000000000 RSI: 0000000020000cc0 RDI: 0000000020000dc0
RBP: 00007fd27b801b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd27b975fa0 R15: 00007fffee0a6c08
 </TASK>

The buggy address belongs to the physical page:
page: refcount:3 mapcount:0 mapping:ffff888031cd4d78 index:0x3f pfn:0x52dc0
memcg:ffff888034852000
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x4fff08000004214(referenced|dirty|workingset|private|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff08000004214 0000000000000000 dead000000000122 ffff888031cd4d78
raw: 000000000000003f ffff88805247c2b8 00000003ffffffff ffff888034852000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x148c40(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 5312, tgid 5311 (syz.0.0), ts 57862673084, free_ts 57791693646
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1558
 prep_new_page mm/page_alloc.c:1566 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3476
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4753
 alloc_pages_mpol_noprof+0x3e1/0x780 mm/mempolicy.c:2269
 alloc_pages_noprof mm/mempolicy.c:2349 [inline]
 folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2356
 filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1000
 __filemap_get_folio+0x41f/0x940 mm/filemap.c:1942
 grow_dev_folio fs/buffer.c:1039 [inline]
 grow_buffers fs/buffer.c:1105 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x1d4/0x670 fs/buffer.c:1431
 getblk_unmovable include/linux/buffer_head.h:369 [inline]
 ext4_getblk+0x31b/0x880 fs/ext4/inode.c:864
 ext4_bread+0x2e/0x180 fs/ext4/inode.c:912
 ext4_append+0x327/0x5c0 fs/ext4/namei.c:83
 make_indexed_dir+0x523/0x1600 fs/ext4/namei.c:2282
 ext4_add_entry+0xcf7/0xfa0 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0x920/0xb50 fs/ext4/namei.c:3438
 vfs_symlink+0x137/0x2e0 fs/namei.c:4669
page last free pid 5313 tgid 5311 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xd3f/0x1010 mm/page_alloc.c:2659
 stack_depot_save_flags+0x7c6/0x940 lib/stackdepot.c:674
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_save_track+0x51/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 shrinker_alloc+0x5a/0x9d0 mm/shrinker.c:685
 alloc_super+0x6c0/0x9d0 fs/super.c:378
 sget_fc+0x34c/0x9c0 fs/super.c:760
 sget_dev fs/super.c:1361 [inline]
 get_tree_bdev_flags+0x257/0x5c0 fs/super.c:1622
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3511
 do_mount fs/namespace.c:3851 [inline]
 __do_sys_mount fs/namespace.c:4061 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4038
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888052dc0f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888052dc0f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888052dc1000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888052dc1080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888052dc1100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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