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BUG: KASAN: use-after-free in rb_left_deepest_node lib/rbtree.c:641 [inline]
BUG: KASAN: use-after-free in rb_next_postorder+0x104/0x140 lib/rbtree.c:661
Read of size 8 at addr ffff8801d5194298 by task syz-executor6/4496

CPU: 0 PID: 4496 Comm: syz-executor6 Not tainted 4.16.0-rc7+ #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 rb_left_deepest_node lib/rbtree.c:641 [inline]
 rb_next_postorder+0x104/0x140 lib/rbtree.c:661
 free_rb_tree_fname+0x4b/0xe0 fs/ext4/dir.c:400
 ext4_htree_free_dir_info fs/ext4/dir.c:426 [inline]
 ext4_release_dir+0x44/0x60 fs/ext4/dir.c:624
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4548b9
RSP: 002b:00007fffde1885c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00000000004548b9
RDX: 000000000040e930 RSI: 0000000000a44bd0 RDI: 0000000000000045
RBP: 00000000004b93e9 R08: 000000000000000b R09: 0000000000000000
R10: 00000000026ce940 R11: 0000000000000246 R12: 00000000026cf940
R13: 0000000000000000 R14: 000000000000001a R15: 0000000000028e25

Allocated by task 4496:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 __do_kmalloc mm/slab.c:3706 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3715
 kmalloc include/linux/slab.h:517 [inline]
 kzalloc include/linux/slab.h:701 [inline]
 ext4_htree_store_dirent+0x8b/0x580 fs/ext4/dir.c:452
 htree_dirblock_to_tree+0x4e8/0xa00 fs/ext4/namei.c:1020
 ext4_htree_fill_tree+0x2bb/0xcb0 fs/ext4/namei.c:1097
 ext4_dx_readdir fs/ext4/dir.c:576 [inline]
 ext4_readdir+0x206a/0x3600 fs/ext4/dir.c:123
 iterate_dir+0x1ca/0x530 fs/readdir.c:51
 SYSC_getdents fs/readdir.c:231 [inline]
 SyS_getdents+0x225/0x450 fs/readdir.c:212
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4496:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kfree+0xd9/0x260 mm/slab.c:3801
 free_rb_tree_fname+0x85/0xe0 fs/ext4/dir.c:404
 ext4_htree_free_dir_info fs/ext4/dir.c:426 [inline]
 ext4_release_dir+0x44/0x60 fs/ext4/dir.c:624
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801d5194280
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 24 bytes inside of
 64-byte region [ffff8801d5194280, ffff8801d51942c0)
The buggy address belongs to the page:
page:ffffea0007546500 count:1 mapcount:0 mapping:ffff8801d5194000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d5194000 0000000000000000 0000000100000020
raw: ffffea00075face0 ffffea0007478b20 ffff8801dac00340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d5194180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801d5194200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801d5194280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff8801d5194300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801d5194380: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
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