blkno = 400000, nblocks = 0
ERROR: (device loop0): dbUpdatePMap.cold: blocks are outside the map
blkno = 400000, nblocks = 0
ERROR: (device loop0): dbFree: block to be freed is outside the map
==================================================================
BUG: KASAN: use-after-free in jfs_lazycommit+0x7c5/0x8c0 fs/jfs/jfs_txnmgr.c:2780
Read of size 4 at addr ffff8880a4159c54 by task jfsCommit/1963

CPU: 1 PID: 1963 Comm: jfsCommit Not tainted 4.14.295-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load4_noabort+0x68/0x70 mm/kasan/report.c:429
 jfs_lazycommit+0x7c5/0x8c0 fs/jfs/jfs_txnmgr.c:2780
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 8164:
 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
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 jfs_fill_super+0x94/0xab0 fs/jfs/super.c:529
 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+0x46/0xbb

Freed by task 8012:
 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
 generic_shutdown_super+0x144/0x370 fs/super.c:446
 kill_block_super+0x95/0xe0 fs/super.c:1161
 deactivate_locked_super+0x6c/0xd0 fs/super.c:319
 deactivate_super+0x7f/0xa0 fs/super.c:350
 cleanup_mnt+0x186/0x2c0 fs/namespace.c:1183
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880a4159bc0
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 148 bytes inside of
 256-byte region [ffff8880a4159bc0, ffff8880a4159cc0)
The buggy address belongs to the page:
page:ffffea0002905640 count:1 mapcount:0 mapping:ffff8880a4159080 index:0xffff8880a4159080
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a4159080 ffff8880a4159080 0000000100000005
raw: ffffea0002a57da0 ffffea0002787fa0 ffff88813fe747c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a4159b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a4159b80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880a4159c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff8880a4159c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880a4159d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================