==================================================================
BUG: KASAN: use-after-free in memset include/linux/string.h:340 [inline]
BUG: KASAN: use-after-free in __ext4_expand_extra_isize+0x16c/0x240 fs/ext4/inode.c:5914
Write of size 2015 at addr ffff88806cc0bba0 by task syz-executor.5/20948

CPU: 0 PID: 20948 Comm: syz-executor.5 Not tainted 5.1.0-rc6+ #82
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+0x172/0x1f0 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:115
 memset include/linux/string.h:340 [inline]
 __ext4_expand_extra_isize+0x16c/0x240 fs/ext4/inode.c:5914
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5966 [inline]
 ext4_mark_inode_dirty+0x6e9/0x940 fs/ext4/inode.c:6042
 ext4_ext_truncate+0x92/0x200 fs/ext4/extents.c:4520
 ext4_truncate+0xe08/0x1440 fs/ext4/inode.c:4526
 ext4_evict_inode+0x9d5/0x18f0 fs/ext4/inode.c:289
 evict+0x309/0x680 fs/inode.c:558
 iput_final fs/inode.c:1547 [inline]
 iput+0x530/0x8d0 fs/inode.c:1573
 dentry_unlink_inode+0x2dc/0x400 fs/dcache.c:374
 __dentry_kill+0x390/0x610 fs/dcache.c:579
 dentry_kill+0xd7/0x5e0 fs/dcache.c:698
 dput+0x570/0x6a0 fs/dcache.c:859
 path_put+0x31/0x70 fs/namei.c:482
 free_fs_struct+0x25/0x70 fs/fs_struct.c:90
 exit_fs+0xf0/0x130 fs/fs_struct.c:107
 do_exit+0x8e0/0x2fa0 kernel/exit.c:872
 do_group_exit+0x135/0x370 kernel/exit.c:980
 get_signal+0x399/0x1d50 kernel/signal.c:2577
 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458d99
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe2f2500cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000073bf08 RCX: 0000000000458d99
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000073bf08
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000073bf0c
R13: 00007fffee1db5bf R14: 00007fe2f25019c0 R15: 000000000073bf0c

The buggy address belongs to the page:
page:ffffea0001b302c0 count:2 mapcount:0 mapping:ffff88809f89f518 index:0x484
def_blk_aops 
flags: 0x1fffc000000203a(referenced|dirty|lru|active|private)
raw: 01fffc000000203a ffffea000228fd88 ffffea000230d848 ffff88809f89f518
raw: 0000000000000484 ffff888099197dc8 00000002ffffffff ffff888060f46c80
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888060f46c80

Memory state around the buggy address:
 ffff88806cc0bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806cc0bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806cc0c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88806cc0c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806cc0c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================