EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=0x00000000000000f0,
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BUG: KASAN: use-after-free in memset include/linux/string.h:337 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x16c/0x240 fs/ext4/inode.c:5922
Write of size 208 at addr ffff88807a9e8fa0 by task rs:main Q:Reg/8187

CPU: 1 PID: 8187 Comm: rs:main Q:Reg Not tainted 4.20.0+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 memset+0x24/0x40 mm/kasan/common.c:113
 memset include/linux/string.h:337 [inline]
 __ext4_expand_extra_isize+0x16c/0x240 fs/ext4/inode.c:5922
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5974 [inline]
 ext4_mark_inode_dirty+0x827/0xb80 fs/ext4/inode.c:6050
 ext4_da_write_end+0x987/0xca0 fs/ext4/inode.c:3193
 generic_perform_write+0x3ce/0x6b0 mm/filemap.c:3219
 __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3333
 ext4_file_write_iter+0x37a/0x1410 fs/ext4/file.c:266
 call_write_iter include/linux/fs.h:1862 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x764/0xb40 fs/read_write.c:487
 vfs_write+0x20c/0x580 fs/read_write.c:549
 ksys_write+0x105/0x260 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f56a510919d
Code: d1 20 00 00 75 10 b8 01 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 be fa ff ff 48 89 04 24 b8 01 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 07 fb ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f56a36aa000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000000000f5 RCX: 00007f56a510919d
RDX: 00000000000000f5 RSI: 0000000001d3a090 RDI: 0000000000000006
RBP: 0000000001d3a090 R08: 0000000001d3a0f9 R09: 0000000001d4fcc0
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007f56a36aa480 R14: 0000000000000003 R15: 0000000001d39e90

The buggy address belongs to the page:
page:ffffea0001ea7a00 count:2 mapcount:0 mapping:ffff88809d49ab18 index:0x427
def_blk_aops 
flags: 0x1fffc000000203a(referenced|dirty|lru|active|private)
raw: 01fffc000000203a ffffea0002b9b808 ffffea0002ffaa08 ffff88809d49ab18
raw: 0000000000000427 ffff8880a6933930 00000002ffffffff ffff8880a9414cc0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8880a9414cc0

Memory state around the buggy address:
 ffff88807a9e8f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807a9e8f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807a9e9000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88807a9e9080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807a9e9100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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