==================================================================
BUG: KASAN: use-after-free in ext4_search_dir+0xf7/0x1b0 fs/ext4/namei.c:1516
Read of size 1 at addr ffff8881190c1900 by task syz.6.18/527

CPU: 1 PID: 527 Comm: syz.6.18 Not tainted 5.10.226-syzkaller-1003449-g6a01908517df #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:452
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 ext4_search_dir+0xf7/0x1b0 fs/ext4/namei.c:1516
 ext4_find_inline_entry+0x4b6/0x5e0 fs/ext4/inline.c:1700
 __ext4_find_entry+0x2b0/0x1990 fs/ext4/namei.c:1589
 ext4_lookup_entry fs/ext4/namei.c:1744 [inline]
 ext4_lookup+0x3c6/0xaa0 fs/ext4/namei.c:1812
 __lookup_hash+0x143/0x290 fs/namei.c:1541
 filename_create+0x202/0x750 fs/namei.c:3608
 user_path_create fs/namei.c:3665 [inline]
 do_mknodat+0x187/0x450 fs/namei.c:3729
 __do_sys_mknod fs/namei.c:3768 [inline]
 __se_sys_mknod fs/namei.c:3766 [inline]
 __x64_sys_mknod+0x80/0x90 fs/namei.c:3766
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fcab4777719
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:00007fcab41f8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007fcab492ef80 RCX: 00007fcab4777719
RDX: 000000000000070d RSI: 0000000000000000 RDI: 0000000020000000
RBP: 00007fcab47ea32e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fcab492ef80 R15: 00007ffc0b1abfc8

Allocated by task 512:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 ____kasan_kmalloc+0xdb/0x110 mm/kasan/common.c:509
 __kasan_kmalloc+0x9/0x10 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 kmem_cache_alloc_trace+0x18a/0x2e0 mm/slub.c:2974
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 call_usermodehelper_setup+0x72/0x1e0 kernel/umh.c:363
 call_modprobe kernel/kmod.c:93 [inline]
 __request_module+0x37d/0x8d0 kernel/kmod.c:170
 dev_load+0x5b/0xb0 net/core/dev_ioctl.c:341
 dev_ioctl+0x3bb/0xb40 net/core/dev_ioctl.c:405
 sock_do_ioctl+0x295/0x3a0 net/socket.c:1090
 sock_ioctl+0x4a6/0x760 net/socket.c:1207
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x114/0x190 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 512:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x121/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1595 [inline]
 slab_free_freelist_hook+0xc0/0x190 mm/slub.c:1621
 slab_free mm/slub.c:3203 [inline]
 kfree+0xc3/0x270 mm/slub.c:4191
 call_usermodehelper_freeinfo kernel/umh.c:45 [inline]
 call_usermodehelper_exec+0x2d3/0x470 kernel/umh.c:452
 call_modprobe kernel/kmod.c:98 [inline]
 __request_module+0x39e/0x8d0 kernel/kmod.c:170
 dev_load+0x5b/0xb0 net/core/dev_ioctl.c:341
 dev_ioctl+0x3bb/0xb40 net/core/dev_ioctl.c:405
 sock_do_ioctl+0x295/0x3a0 net/socket.c:1090
 sock_ioctl+0x4a6/0x760 net/socket.c:1207
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x114/0x190 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff8881190c1900
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
 128-byte region [ffff8881190c1900, ffff8881190c1980)
The buggy address belongs to the page:
page:ffffea0004643040 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1190c1
flags: 0x4000000000000200(slab)
raw: 4000000000000200 dead000000000100 dead000000000122 ffff888100043500
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
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 512, ts 54295447762, free_ts 54242727278
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x166/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2d8c/0x2f30 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x435/0xaf0 mm/page_alloc.c:5348
 allocate_slab mm/slub.c:1808 [inline]
 new_slab+0x80/0x400 mm/slub.c:1869
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x302/0x4b0 mm/slub.c:2791
 __slab_alloc+0x63/0xa0 mm/slub.c:2831
 slab_alloc_node mm/slub.c:2913 [inline]
 slab_alloc mm/slub.c:2955 [inline]
 kmem_cache_alloc_trace+0x1bd/0x2e0 mm/slub.c:2972
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 call_usermodehelper_setup+0x72/0x1e0 kernel/umh.c:363
 call_modprobe kernel/kmod.c:93 [inline]
 __request_module+0x37d/0x8d0 kernel/kmod.c:170
 dev_load+0x5b/0xb0 net/core/dev_ioctl.c:341
 dev_ioctl+0x3bb/0xb40 net/core/dev_ioctl.c:405
 sock_do_ioctl+0x295/0x3a0 net/socket.c:1090
 sock_ioctl+0x4a6/0x760 net/socket.c:1207
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x114/0x190 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x34/0x70
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_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2ae/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page+0x9e/0x370 mm/page_alloc.c:5407
 __free_pages+0x67/0xc0 mm/page_alloc.c:5418
 __free_slab+0xcf/0x190 mm/slub.c:1894
 free_slab mm/slub.c:1909 [inline]
 discard_slab mm/slub.c:1915 [inline]
 unfreeze_partials+0x15e/0x190 mm/slub.c:2410
 put_cpu_partial+0xbf/0x180 mm/slub.c:2446
 __slab_free+0x2c8/0x3a0 mm/slub.c:3095
 do_slab_free mm/slub.c:3191 [inline]
 ___cache_free+0x111/0x130 mm/slub.c:3210
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x47/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x15a/0x170 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x61/0x2f0 mm/slab.h:583
 slab_alloc_node mm/slub.c:2947 [inline]
 slab_alloc mm/slub.c:2955 [inline]
 kmem_cache_alloc_trace+0x163/0x2e0 mm/slub.c:2972
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 ipv6_add_addr+0x419/0xd40 net/ipv6/addrconf.c:1112
 addrconf_add_linklocal+0x318/0x9e0 net/ipv6/addrconf.c:3253

Memory state around the buggy address:
 ffff8881190c1800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881190c1880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881190c1900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8881190c1980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881190c1a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
EXT4-fs error (device loop6): ext4_find_dest_de:2077: inode #12: block 7: comm syz.6.18: bad entry in directory: directory entry overrun - offset=0, inode=1793120026, rec_len=34652, size=56 fake=0