IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
==================================================================
BUG: KASAN: use-after-free in ext4_data_block_valid+0x2d5/0x330 fs/ext4/block_validity.c:211
Read of size 8 at addr ffff8801c9ff1280 by task jbd2/sda1-8/3304

CPU: 0 PID: 3304 Comm: jbd2/sda1-8 Not tainted 4.19.0-rc6-next-20181005+ #88
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+0x1d3/0x2c4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ext4_data_block_valid+0x2d5/0x330 fs/ext4/block_validity.c:211
 __check_block_validity.constprop.79+0xc1/0x210 fs/ext4/inode.c:402
 ext4_map_blocks+0x1029/0x1b60 fs/ext4/inode.c:592
 _ext4_get_block+0x226/0x6d0 fs/ext4/inode.c:783
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:800
 generic_block_bmap+0x16c/0x250 fs/buffer.c:2999
 ext4_bmap+0x1fd/0x420 fs/ext4/inode.c:3344
 bmap+0x93/0xc0 fs/inode.c:1593
 jbd2_journal_bmap+0x57/0xf0 fs/jbd2/journal.c:819
 jbd2_journal_next_log_block+0x102/0x170 fs/jbd2/journal.c:802
 jbd2_journal_get_descriptor_buffer+0x97/0x410 fs/jbd2/journal.c:854
 journal_submit_commit_record+0x149/0xb60 fs/jbd2/commit.c:131
 jbd2_journal_commit_transaction+0x61ca/0x89da fs/jbd2/commit.c:860
 kjournald2+0x26d/0xb30 fs/jbd2/journal.c:229
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 1:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554
 add_system_zone+0x2e5/0x5f0 fs/ext4/block_validity.c:85
 ext4_setup_system_zone+0x360/0x520 fs/ext4/block_validity.c:160
 ext4_fill_super+0x8181/0xdab0 fs/ext4/super.c:4368
 mount_bdev+0x314/0x3e0 fs/super.c:1356
 ext4_mount+0x3c/0x50 fs/ext4/super.c:5872
 legacy_get_tree+0x131/0x460 fs/fs_context.c:718
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1795
 do_new_mount fs/namespace.c:2648 [inline]
 do_mount+0x70c/0x1d90 fs/namespace.c:2974
 ksys_mount+0x12d/0x140 fs/namespace.c:3190
 do_mount_root+0x35/0x1d3 init/do_mounts.c:388
 mount_block_root+0x39c/0x6ed init/do_mounts.c:417
 mount_root+0x2d3/0x31a init/do_mounts.c:562
 prepare_namespace+0x26c/0x2ab init/do_mounts.c:621
 kernel_init_freeable+0x590/0x5ae init/main.c:1162
 kernel_init+0x11/0x1b2 init/main.c:1063
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 13899:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x83/0x290 mm/slab.c:3760
 ext4_release_system_zone+0x92/0x110 fs/ext4/block_validity.c:187
 ext4_setup_system_zone+0x3ef/0x520 fs/ext4/block_validity.c:151
 ext4_remount+0x1451/0x2640 fs/ext4/super.c:5320
 legacy_reconfigure+0x14c/0x1c0 fs/fs_context.c:754
 reconfigure_super+0x4c0/0xbb0 fs/super.c:982
 do_remount fs/namespace.c:2419 [inline]
 do_mount+0x18b9/0x1d90 fs/namespace.c:2965
 ksys_mount+0x12d/0x140 fs/namespace.c:3190
 __do_sys_mount fs/namespace.c:3204 [inline]
 __se_sys_mount fs/namespace.c:3201 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3201
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801c9ff1268
 which belongs to the cache ext4_system_zone of size 40
The buggy address is located 24 bytes inside of
 40-byte region [ffff8801c9ff1268, ffff8801c9ff1290)
The buggy address belongs to the page:
page:ffffea000727fc40 count:1 mapcount:0 mapping:ffff8801d4bbc600 index:0xffff8801c9ff1fb9
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffff8801d4bbb438 ffff8801d4bbb438 ffff8801d4bbc600
raw: ffff8801c9ff1fb9 ffff8801c9ff1000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c9ff1180: fc fb fb fb fb fb fc fc fb fb fb fb fb fc fc fb
 ffff8801c9ff1200: fb fb fb fb fc fc fb fb fb fb fb fc fc fb fb fb
>ffff8801c9ff1280: fb fb fc fc fb fb fb fb fb fc fc fb fb fb fb fb
                   ^
 ffff8801c9ff1300: fc fc fb fb fb fb fb fc fc fb fb fb fb fb fc fc
 ffff8801c9ff1380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
EXT4-fs (sda1): re-mounted. Opts: noblock_validity,grpid,usrquota,errors=continue,jqfmt=vfsv0,,errors=continue