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BUG: KASAN: use-after-free in __list_add_valid+0xb1/0xd0 lib/list_debug.c:23
Read of size 8 at addr ffff8801a87ad638 by task syz-executor0/4446

CPU: 0 PID: 4446 Comm: syz-executor0 Not tainted 4.16.0-rc7+ #7
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
 __list_add_valid+0xb1/0xd0 lib/list_debug.c:23
 __list_add include/linux/list.h:60 [inline]
 list_add include/linux/list.h:79 [inline]
 list_move include/linux/list.h:171 [inline]
 inode_io_list_move_locked+0x22a/0x4d0 fs/fs-writeback.c:141
 __mark_inode_dirty+0x75c/0x1170 fs/fs-writeback.c:2205
 generic_update_time+0x2a2/0x370 fs/inode.c:1653
 update_time fs/inode.c:1669 [inline]
 touch_atime+0x26d/0x2f0 fs/inode.c:1741
 file_accessed include/linux/fs.h:2060 [inline]
 iterate_dir+0x451/0x530 fs/readdir.c:56
 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
RIP: 0033:0x45337b
RSP: 002b:00007fffd23f73c0 EFLAGS: 00000206 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000002929970 RCX: 000000000045337b
RDX: 0000000000008000 RSI: 0000000002929970 RDI: 0000000000000003
RBP: 0000000002929970 R08: 0000000000000001 R09: 0000000002928940
R10: 0000000000000000 R11: 0000000000000206 R12: ffffffffffffffd4
R13: 0000000000000016 R14: 0000000000000067 R15: 0000000000006f19

Allocated by task 5553:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 slab_post_alloc_hook mm/slab.h:443 [inline]
 slab_alloc mm/slab.c:3380 [inline]
 kmem_cache_alloc+0x11b/0x760 mm/slab.c:3540
 ext4_alloc_inode+0xc1/0x7e0 fs/ext4/super.c:968
 alloc_inode+0x65/0x180 fs/inode.c:209
 new_inode_pseudo+0x69/0x190 fs/inode.c:890
 new_inode+0x1c/0x40 fs/inode.c:919
 __ext4_new_inode+0x3a0/0x4e80 fs/ext4/ialloc.c:859
 ext4_symlink+0x41e/0x1060 fs/ext4/namei.c:3094
 vfs_symlink+0x323/0x560 fs/namei.c:4105
 SYSC_symlinkat fs/namei.c:4132 [inline]
 SyS_symlinkat+0x1dd/0x250 fs/namei.c:4112
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 2700:
 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]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 ext4_i_callback+0x20/0x30 fs/ext4/super.c:1011
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2674 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline]
 rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801a87ad2c0
 which belongs to the cache ext4_inode_cache(49:syz0) of size 1968
The buggy address is located 888 bytes inside of
 1968-byte region [ffff8801a87ad2c0, ffff8801a87ada70)
The buggy address belongs to the page:
page:ffffea0006a1eb40 count:1 mapcount:0 mapping:ffff8801a87ad2c0 index:0xffff8801a87adfff
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801a87ad2c0 ffff8801a87adfff 0000000100000001
raw: ffffea0006c2afe0 ffff8801d4784e48 ffff8801cd556940 ffff8801b1316100
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801b1316100

Memory state around the buggy address:
 ffff8801a87ad500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a87ad580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801a87ad600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff8801a87ad680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801a87ad700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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