==================================================================
BUG: KASAN: slab-out-of-bounds in find_first_zero_bit+0x84/0x90 lib/find_bit.c:105
Read of size 8 at addr ffff8880a8c2e400 by task syz-executor.0/9592

CPU: 0 PID: 9592 Comm: syz-executor.0 Not tainted 4.14.307-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:251
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:350
 kasan_report mm/kasan/report.c:408 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:429
 find_first_zero_bit+0x84/0x90 lib/find_bit.c:105
 bfs_create+0xfb/0x620 fs/bfs/dir.c:92
 lookup_open+0x77a/0x1750 fs/namei.c:3241
 do_last fs/namei.c:3334 [inline]
 path_openat+0xe08/0x2970 fs/namei.c:3571
 do_filp_open+0x179/0x3c0 fs/namei.c:3605
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3
RIP: 0033:0x7f7030a4f0f9
RSP: 002b:00007f702efc1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7030b6ef80 RCX: 00007f7030a4f0f9
RDX: 000000000000275a RSI: 0000000020000400 RDI: ffffffffffffff9c
RBP: 00007f7030aaaae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc0aa715ef R14: 00007f702efc1300 R15: 0000000000022000

Allocated by task 9592:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 bfs_fill_super+0x3d5/0xd80 fs/bfs/inode.c:363
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 do_mount+0xe65/0x2a30 fs/namespace.c:2905
 SYSC_mount fs/namespace.c:3121 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3098
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3

Freed by task 4631:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 kobject_uevent_env+0x26c/0xf30 lib/kobject_uevent.c:537
 kobject_synth_uevent+0x5b6/0x6d0 lib/kobject_uevent.c:205
 uevent_store+0x3c/0x80 drivers/base/bus.c:621
 drv_attr_store+0x6d/0xa0 drivers/base/bus.c:78
 sysfs_kf_write+0x106/0x160 fs/sysfs/file.c:142
 kernfs_fop_write+0x289/0x440 fs/kernfs/file.c:316
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3

The buggy address belongs to the object at ffff8880a8c2e400
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880a8c2e400, ffff8880a8c2e420)
The buggy address belongs to the page:
page:ffffea0002a30b80 count:1 mapcount:0 mapping:ffff8880a8c2e000 index:0xffff8880a8c2efc1
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a8c2e000 ffff8880a8c2efc1 000000010000003f
raw: ffffea0002989b60 ffffea0002a3cf60 ffff88813fe741c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a8c2e300: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a8c2e380: 00 03 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a8c2e400: 07 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
                   ^
 ffff8880a8c2e480: 00 00 00 00 fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a8c2e500: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================
attempt to access beyond end of device
loop3: rw=2049, want=45104, limit=40427
rock: corrupted directory entry. extent=32, offset=2044, size=237