EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=64648
EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=64648
EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=64648
EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=64648
==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:330 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x178/0x240 fs/ext4/inode.c:5789
Write of size 64616 at addr ffff8801c3a660a0 by task syz-executor956/4449

CPU: 0 PID: 4449 Comm: syz-executor956 Not tainted 4.17.0-rc7+ #80
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+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe 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:330 [inline]
 __ext4_expand_extra_isize+0x178/0x240 fs/ext4/inode.c:5789
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5841 [inline]
 ext4_mark_inode_dirty+0x72f/0xb20 fs/ext4/inode.c:5917
 ext4_dirty_inode+0x97/0xc0 fs/ext4/inode.c:5951
 __mark_inode_dirty+0x811/0x1530 fs/fs-writeback.c:2129
 generic_update_time+0x255/0x420 fs/inode.c:1657
 update_time fs/inode.c:1673 [inline]
 touch_atime+0x292/0x310 fs/inode.c:1745
 file_accessed include/linux/fs.h:2063 [inline]
 iterate_dir+0x394/0x5d0 fs/readdir.c:56
 __do_sys_getdents fs/readdir.c:231 [inline]
 __se_sys_getdents fs/readdir.c:212 [inline]
 __x64_sys_getdents+0x293/0x4e0 fs/readdir.c:212
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445ceb
RSP: 002b:00007ffd5d921990 EFLAGS: 00000206 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000002672990 RCX: 0000000000445ceb
RDX: 0000000000008000 RSI: 0000000002672990 RDI: 0000000000000003
RBP: 0000000002672990 R08: 0000000000001161 R09: 0000000002671940
R10: 0000000000000000 R11: 0000000000000206 R12: ffffffffffffffd4
R13: 0000000000000016 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00070e9980 count:2 mapcount:0 mapping:ffff8801ce85e660 index:0x4a8
flags: 0x2fffc0000001064(referenced|lru|active|private)
raw: 02fffc0000001064 ffff8801ce85e660 00000000000004a8 00000002ffffffff
raw: ffffea00070e9960 ffffea00070e99e0 ffff8801aee00348 ffff8801d9a42c80
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801d9a42c80

Memory state around the buggy address:
 ffff8801c3a6cf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801c3a6cf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8801c3a6d000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8801c3a6d080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801c3a6d100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================