BFS-fs: bfs_fill_super(): Impossible last inode number 873 > 513 on loop4
BFS-fs: bfs_fill_super(): No BFS filesystem on loop1 (magic=00000000)
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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+0x16c/0x240 fs/ext4/inode.c:5923
Write of size 256 at addr ffff88806974c080 by task syz-executor0/28819

CPU: 0 PID: 28819 Comm: syz-executor0 Not tainted 5.0.0-rc2+ #31
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+0x1db/0x2d0 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:113
 memset include/linux/string.h:337 [inline]
 __ext4_expand_extra_isize+0x16c/0x240 fs/ext4/inode.c:5923
 ext4_try_to_expand_extra_isize fs/ext4/inode.c:5975 [inline]
 ext4_mark_inode_dirty+0x827/0xb80 fs/ext4/inode.c:6051
 ext4_dirty_inode+0x8f/0xc0 fs/ext4/inode.c:6085
 __mark_inode_dirty+0xab5/0x1590 fs/fs-writeback.c:2122
 generic_update_time+0x268/0x440 fs/inode.c:1654
 update_time fs/inode.c:1670 [inline]
 touch_atime+0x2a4/0x320 fs/inode.c:1741
 get_link fs/namei.c:1057 [inline]
 trailing_symlink+0x2d4/0x970 fs/namei.c:2263
 path_mountpoint+0x9ee/0x21a0 fs/namei.c:2696
 filename_mountpoint+0x258/0x490 fs/namei.c:2717
 user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2747
 ksys_umount+0x198/0x1340 fs/namespace.c:1643
 __do_sys_umount fs/namespace.c:1669 [inline]
 __se_sys_umount fs/namespace.c:1667 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1667
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45aae7
Code: 44 00 00 b8 08 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 0d 8d fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 ed 8c fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe0818c778 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 00000000000fd537 RCX: 000000000045aae7
RDX: 0000000000402eb0 RSI: 0000000000000002 RDI: 00007ffe0818c820
RBP: 0000000000000715 R08: 0000000000000000 R09: 0000000000000010
R10: 000000000000000a R11: 0000000000000202 R12: 00007ffe0818d8b0
R13: 00000000023c5940 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0001a5d300 count:0 mapcount:-128 mapping:0000000000000000 index:0x1
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 ffffea0001e51608 ffffea0001e09e08 0000000000000000
raw: 0000000000000001 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806974bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806974c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806974c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88806974c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806974c180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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