audit: type=1400 audit(2000000733.740:62594): avc:  denied  { map } for  pid=5943 comm="blkid" path="/lib/x86_64-linux-gnu/libuuid.so.1.3.0" dev="sda1" ino=2819 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1
EXT4-fs (sda1): re-mounted. Opts: debug_want_extra_isize=0x000000000000ffff,
==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:329 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize.isra.13+0x108/0x1b0 fs/ext4/inode.c:5781
Write of size 65503 at addr ffff8881937551a0 by task syz-executor4/1846

CPU: 0 PID: 1846 Comm: syz-executor4 Not tainted 4.14.87+ #19
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 print_address_description+0x60/0x22b mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
 memset+0x1f/0x40 mm/kasan/kasan.c:285
 memset include/linux/string.h:329 [inline]
 __ext4_expand_extra_isize.isra.13+0x108/0x1b0 fs/ext4/inode.c:5781
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5833 [inline]
 ext4_mark_inode_dirty+0x46c/0x7e0 fs/ext4/inode.c:5909
 ext4_dirty_inode+0x71/0xa0 fs/ext4/inode.c:5943
 __mark_inode_dirty+0x108/0x1060 fs/fs-writeback.c:2097
 generic_update_time+0x1a5/0x270 fs/inode.c:1650
 update_time fs/inode.c:1666 [inline]
 touch_atime+0x210/0x270 fs/inode.c:1738
 file_accessed include/linux/fs.h:2083 [inline]
 iterate_dir+0x4c3/0x5e0 fs/readdir.c:57
 SYSC_getdents fs/readdir.c:232 [inline]
 SyS_getdents+0x146/0x270 fs/readdir.c:213
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45594b
RSP: 002b:00007ffc5b468b40 EFLAGS: 00000202 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000001c93970 RCX: 000000000045594b
RDX: 0000000000008000 RSI: 0000000001c93970 RDI: 0000000000000003
RBP: 0000000001c93970 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000005 R11: 0000000000000202 R12: ffffffffffffffd4
R13: 0000000000000016 R14: 0000000000000000 R15: 0000000000000004

The buggy address belongs to the page:
page:ffffea00064dd540 count:2 mapcount:0 mapping:ffff8881d56a8950 index:0x436
flags: 0x4000000000001074(referenced|dirty|lru|active|private)
raw: 4000000000001074 ffff8881d56a8950 0000000000000436 00000002ffffffff
raw: ffffea00065ba420 ffffea00064dd220 ffff8881bf679dc8 ffff8881d641aa80
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8881d641aa80

Memory state around the buggy address:
 ffff888193758f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888193758f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888193759000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888193759080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888193759100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================