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BUG: KASAN: use-after-free in dx_insert_block fs/ext4/namei.c:1358 [inline]
BUG: KASAN: use-after-free in do_split+0x19d7/0x1e90 fs/ext4/namei.c:2044
Read of size 157024 at addr ffff888111b1b028 by task syz.4.38/606

CPU: 1 PID: 606 Comm: syz.4.38 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block fs/ext4/namei.c:1358 [inline]
 do_split+0x19d7/0x1e90 fs/ext4/namei.c:2044
 make_indexed_dir+0xe14/0x1460 fs/ext4/namei.c:2348
 ext4_add_entry+0xd80/0xf90 fs/ext4/namei.c:2460
 __ext4_link+0x4d6/0x760 fs/ext4/namei.c:3647
 ext4_link+0x1ee/0x290 fs/ext4/namei.c:3688
 vfs_link+0x684/0x880 fs/namei.c:4221
 do_linkat+0x381/0x670 fs/namei.c:4289
 __do_sys_link fs/namei.c:4318 [inline]
 __se_sys_link fs/namei.c:4316 [inline]
 __x64_sys_link+0x68/0x80 fs/namei.c:4316
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fd941304999
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:00007fd940d58058 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007fd9414d0080 RCX: 00007fd941304999
RDX: 0000000000000000 RSI: 0000000020000bc0 RDI: 0000000020001240
RBP: 00007fd941387a05 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd9414d0080 R15: 00007ffdc844f1f8

The buggy address belongs to the page:
page:ffffea000446c6c0 refcount:3 mapcount:1 mapping:ffff8881092fe8d0 index:0x1 pfn:0x111b1b
aops:def_blk_aops ino:0
flags: 0x400000000032201e(referenced|uptodate|dirty|lru|private|mappedtodisk|unevictable|mlocked)
raw: 400000000032201e ffff888100194040 ffffea000446c688 ffff8881092fe8d0
raw: 0000000000000001 ffff8881219cb5e8 0000000300000000 ffff888100142000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888100142000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 542, ts 44241165137, free_ts 44036606847
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 __page_cache_alloc include/linux/pagemap.h:290 [inline]
 page_cache_ra_unbounded+0x2d2/0x790 mm/readahead.c:226
 do_page_cache_ra mm/readahead.c:277 [inline]
 force_page_cache_ra+0x3a7/0x400 mm/readahead.c:308
 page_cache_sync_ra+0x237/0x2a0 mm/readahead.c:582
 page_cache_sync_readahead include/linux/pagemap.h:837 [inline]
 generic_file_buffered_read+0x570/0x26d0 mm/filemap.c:2250
 generic_file_read_iter+0x10b/0x580 mm/filemap.c:2568
 blkdev_read_iter+0x12f/0x160 fs/block_dev.c:1956
 call_read_iter include/linux/fs.h:2060 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x62a/0xa50 fs/read_write.c:496
 ksys_read+0x14a/0x260 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:642
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5445 [inline]
 __free_pages+0xd8/0x390 mm/page_alloc.c:5454
 kfree+0x1e4/0x270 mm/slub.c:4193
 kvfree+0x35/0x40 mm/util.c:647
 wg_destruct+0x299/0x300 drivers/net/wireguard/device.c:249
 netdev_run_todo+0xb5e/0xda0 net/core/dev.c:10352
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112
 default_device_exit_batch+0x363/0x3c0 net/core/dev.c:11299
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x5fe/0xb80 net/core/net_namespace.c:609
 process_one_work+0x6fd/0xbc0 kernel/workqueue.c:2301
 worker_thread+0xa8e/0x13c0 kernel/workqueue.c:2447
 kthread+0x324/0x3b0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

Memory state around the buggy address:
 ffff888111b1ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888111b1ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888111b20000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888111b20080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888111b20100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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EXT4-fs error (device loop4): ext4_dx_csum_set:529: inode #2: comm syz.4.38: dir seems corrupt?  Run e2fsck -D.