EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=0x0000000000007a00,
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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+0x16f/0x240 fs/ext4/inode.c:5897
Write of size 31200 at addr ffff88818dd073a0 by task syz-executor2/24485

CPU: 0 PID: 24485 Comm: syz-executor2 Not tainted 4.20.0-rc4+ #140
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+0x244/0x39d lib/dump_stack.c:113
 print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memset+0x23/0x40 mm/kasan/kasan.c:285
 memset include/linux/string.h:337 [inline]
 __ext4_expand_extra_isize+0x16f/0x240 fs/ext4/inode.c:5897
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5949 [inline]
 ext4_mark_inode_dirty+0x8f9/0xb20 fs/ext4/inode.c:6025
 ext4_dirty_inode+0x97/0xc0 fs/ext4/inode.c:6059
 __mark_inode_dirty+0x7c3/0x1510 fs/fs-writeback.c:2122
IPVS: ftp: loaded support on port[0] = 21
 generic_update_time+0x26a/0x450 fs/inode.c:1654
 update_time fs/inode.c:1670 [inline]
 file_update_time+0x390/0x640 fs/inode.c:1880
 ext4_page_mkwrite+0x1fe/0x14a0 fs/ext4/inode.c:6204
 do_page_mkwrite+0x15c/0x770 mm/memory.c:2144
 do_shared_fault mm/memory.c:3473 [inline]
 do_fault mm/memory.c:3538 [inline]
 handle_pte_fault mm/memory.c:3765 [inline]
 __handle_mm_fault+0x3d54/0x5be0 mm/memory.c:3889
 handle_mm_fault+0x54f/0xc70 mm/memory.c:3926
 do_user_addr_fault arch/x86/mm/fault.c:1423 [inline]
 __do_page_fault+0x5e8/0xe60 arch/x86/mm/fault.c:1489
 do_page_fault+0xf2/0x7e0 arch/x86/mm/fault.c:1520
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1139
RIP: 0033:0x4016d7
Code: 00 00 00 48 83 ec 08 48 8b 15 75 e9 63 00 48 8b 05 66 e9 63 00 48 39 d0 48 8d 8a 00 00 00 01 72 17 48 39 c8 73 12 48 8d 50 04 <89> 38 48 89 15 48 e9 63 00 48 83 c4 08 c3 48 89 c6 bf b0 5e 4c 00
RSP: 002b:00007ffd16b47ff0 EFLAGS: 00010287
RAX: 0000001b2ca23000 RBX: 00000000efa58ce6 RCX: 0000001b2da20000
RDX: 0000001b2ca23004 RSI: 0000000000000c98 RDI: ffffffff27530c98
RBP: 0000000000000656 R08: 0000000027530c98 R09: 0000000027530c9c
R10: 00007ffd16b48190 R11: 0000000000000246 R12: 000000000072bf00
R13: 0000000080000000 R14: 00007fc9d529a008 R15: 0000000000028dc9

The buggy address belongs to the page:
page:ffffea00063741c0 count:2 mapcount:0 mapping:ffff8881cc4c2658 index:0x429
flags: 0x2fffc000000203a(referenced|dirty|lru|active|private)
raw: 02fffc000000203a ffffea0006393a48 ffffea0006374208 ffff8881cc4c2658
raw: 0000000000000429 ffff8881d489a2a0 00000002ffffffff ffff8881d9a4adc0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8881d9a4adc0

Memory state around the buggy address:
 ffff88818dd0bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88818dd0bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88818dd0c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88818dd0c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88818dd0c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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