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BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
Read of size 2 at addr ffff888083f3a000 by task syz-executor.4/5773

CPU: 1 PID: 5773 Comm: syz-executor.4 Not tainted 4.14.198-syzkaller #0
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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load2_noabort+0x68/0x70 mm/kasan/report.c:428
 __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
 ext4_readdir+0x7fd/0x27e0 fs/ext4/dir.c:240
 iterate_dir+0x1a0/0x5e0 fs/readdir.c:52
 SYSC_getdents fs/readdir.c:269 [inline]
 SyS_getdents+0x125/0x240 fs/readdir.c:250
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45e179
RSP: 002b:00007f47c054ac78 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000000003f80 RCX: 000000000045e179
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffea993dbef R14: 00007f47c054b9c0 R15: 000000000118cf4c

Allocated by task 6383:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc_node_trace+0x153/0x400 mm/slab.c:3661
 kmalloc_node include/linux/slab.h:526 [inline]
 alloc_vmap_area+0xf0/0x7c0 mm/vmalloc.c:420
 __get_vm_area_node+0x126/0x340 mm/vmalloc.c:1414
 __vmalloc_node_range mm/vmalloc.c:1762 [inline]
 __vmalloc_node mm/vmalloc.c:1818 [inline]
 __vmalloc_node_flags mm/vmalloc.c:1832 [inline]
 vzalloc+0x98/0x150 mm/vmalloc.c:1871
 do_ip6t_get_ctl+0x438/0x7d0 net/ipv6/netfilter/ip6_tables.c:818
 nf_sockopt net/netfilter/nf_sockopt.c:104 [inline]
 nf_getsockopt+0x62/0xc0 net/netfilter/nf_sockopt.c:122
 ipv6_getsockopt+0x146/0x1e0 net/ipv6/ipv6_sockglue.c:1376
 tcp_getsockopt+0x7b/0xc0 net/ipv4/tcp.c:3257
 SYSC_getsockopt net/socket.c:1896 [inline]
 SyS_getsockopt+0x102/0x1c0 net/socket.c:1878
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 7:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 __rcu_reclaim kernel/rcu/rcu.h:190 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x88b/0x1180 kernel/rcu/tree.c:2946
 __do_softirq+0x254/0xa1d kernel/softirq.c:288

The buggy address belongs to the object at ffff888083f3a000
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
 96-byte region [ffff888083f3a000, ffff888083f3a060)
The buggy address belongs to the page:
page:ffffea00020fce80 count:1 mapcount:0 mapping:ffff888083f3a000 index:0xffff888083f3ac80
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff888083f3a000 ffff888083f3ac80 000000010000000a
raw: ffffea000291ade0 ffffea00022ffee0 ffff88812fe504c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888083f39f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888083f39f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888083f3a000: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                   ^
 ffff888083f3a080: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff888083f3a100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
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