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BUG: KASAN: slab-out-of-bounds in find_first_zero_bit+0x84/0x90 lib/find_bit.c:105
Read of size 8 at addr ffff88809dfd0740 by task syz-executor.5/10713

CPU: 0 PID: 10713 Comm: syz-executor.5 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: 0033:0x7fa2869c90f9
RSP: 002b:00007fa284f3b168 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007fa286ae8f80 RCX: 00007fa2869c90f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200001c0
RBP: 00007fa286a24ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdcb7a9b9f R14: 00007fa284f3b300 R15: 0000000000022000

Allocated by task 10713:
 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 9968:
 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
 do_delayed_call include/linux/delayed_call.h:28 [inline]
 put_link fs/namei.c:900 [inline]
 step_into fs/namei.c:1787 [inline]
 walk_component+0x1bf/0xbc0 fs/namei.c:1844
 link_path_walk+0x4cb/0x10a0 fs/namei.c:2151
 path_openat+0x15e/0x2970 fs/namei.c:3570
 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

The buggy address belongs to the object at ffff88809dfd0740
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff88809dfd0740, ffff88809dfd0760)
The buggy address belongs to the page:
page:ffffea000277f400 count:1 mapcount:0 mapping:ffff88809dfd0000 index:0xffff88809dfd0fc1
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff88809dfd0000 ffff88809dfd0fc1 000000010000003a
raw: ffffea0002a9dee0 ffffea0002a350a0 ffff88813fe741c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809dfd0600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88809dfd0680: fb fb fb fb fc fc fc fc 00 00 03 fc fc fc fc fc
>ffff88809dfd0700: 00 04 fc fc fc fc fc fc 07 fc fc fc fc fc fc fc
                                           ^
 ffff88809dfd0780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88809dfd0800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
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