==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:332 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize.isra.0+0x10b/0x1c0 fs/ext4/inode.c:5795
Write of size 2715 at addr ffff8881b9c72aa0 by task syz-executor.2/24651

CPU: 0 PID: 24651 Comm: syz-executor.2 Not tainted 4.14.146+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 memset+0x20/0x40 mm/kasan/common.c:113
 memset include/linux/string.h:332 [inline]
 __ext4_expand_extra_isize.isra.0+0x10b/0x1c0 fs/ext4/inode.c:5795
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5847 [inline]
 ext4_mark_inode_dirty+0x471/0x7f0 fs/ext4/inode.c:5923
 ext4_evict_inode+0x6a6/0x1560 fs/ext4/inode.c:282
 evict+0x2cb/0x5f0 fs/inode.c:554
 iput_final fs/inode.c:1516 [inline]
 iput fs/inode.c:1543 [inline]
 iput+0x385/0x7f0 fs/inode.c:1528
 dentry_unlink_inode+0x25f/0x320 fs/dcache.c:387
 __dentry_kill+0x325/0x560 fs/dcache.c:591
 dentry_kill fs/dcache.c:632 [inline]
 dput.part.0+0x4b5/0x710 fs/dcache.c:847
 dput+0x1b/0x30 fs/dcache.c:811
 path_put+0x2d/0x60 fs/namei.c:519
 free_fs_struct+0x1e/0x60 fs/fs_struct.c:91
 exit_fs+0xdc/0x110 fs/fs_struct.c:109
 do_exit+0x9a8/0x2a20 kernel/exit.c:871
 do_group_exit+0x100/0x2e0 kernel/exit.c:978
 get_signal+0x39f/0x1cc0 kernel/signal.c:2422
 do_signal+0x96/0x15d0 arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x11d/0x160 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x3a3/0x520 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459a29
RSP: 002b:00007f0f9a2dfcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459a29
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00007ffd21111c5f R14: 00007f0f9a2e09c0 R15: 000000000075bf2c

The buggy address belongs to the page:
page:ffffea0006e71c80 count:2 mapcount:0 mapping:ffff8881d9ab8950 index:0x498
flags: 0x400000000000203a(referenced|dirty|lru|active|private)
raw: 400000000000203a ffff8881d9ab8950 0000000000000498 00000002ffffffff
raw: ffffea00067f05e0 ffffea0006d4ffe0 ffff88819d115690 ffff8881da81aa80
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8881da81aa80

Memory state around the buggy address:
 ffff8881b9c72f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881b9c72f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881b9c73000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff f