bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67
building syzkaller on 9602ddf403bdf3cfd87efef14becc76f9a38b81d
testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0
kernel signature: 73d21cbfd5daaf582d7dfff591a1a68faf647015a77d5185ebe48c57c72011fa
all runs: crashed: KASAN: use-after-free Read in ntfs_iget
testing current HEAD 87335852c5d9ec629f80bb2257b9a9945962b719
testing commit 87335852c5d9ec629f80bb2257b9a9945962b719 with gcc (GCC) 8.1.0
kernel signature: 6636986e3332e663c725bb8e868471265490b1413e3b2a76c009975637a94b89
run #0: crashed: KASAN: use-after-free Read in ntfs_iget
run #1: crashed: KASAN: use-after-free Read in ntfs_iget
run #2: crashed: KASAN: use-after-free Read in ntfs_iget
run #3: crashed: KASAN: use-after-free Read in ntfs_iget
run #4: crashed: KASAN: use-after-free Read in ntfs_iget
run #5: crashed: KASAN: use-after-free Read in ntfs_iget
run #6: crashed: KASAN: out-of-bounds Read in ntfs_iget
run #7: crashed: KASAN: use-after-free Read in ntfs_iget
run #8: crashed: KASAN: use-after-free Read in ntfs_iget
run #9: crashed: KASAN: use-after-free Read in ntfs_iget
revisions tested: 2, total time: 25m22.309471629s (build: 19m2.249689268s, test: 5m45.24635383s)
the crash still happens on HEAD
commit msg: Linux 4.14.209
crash: KASAN: use-after-free Read in ntfs_iget
IPv6: ADDRCONF(NETDEV_CHANGE): macsec0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_0: link becomes ready
==================================================================
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_batadv: link becomes ready
BUG: KASAN: use-after-free in ntfs_read_locked_inode+0x418b/0x51d0 fs/ntfs/inode.c:677
Read of size 8 at addr ffff8881c7d5e6cd by task syz-executor.2/7317

CPU: 0 PID: 7317 Comm: syz-executor.2 Not tainted 4.14.209-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x14b/0x1f1 lib/dump_stack.c:58
 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.7+0x11a/0x2d4 mm/kasan/report.c:409
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
 ntfs_read_locked_inode+0x418b/0x51d0 fs/ntfs/inode.c:677
 ntfs_iget+0xda/0x110 fs/ntfs/inode.c:190
 load_and_init_attrdef fs/ntfs/super.c:1603 [inline]
 load_system_files fs/ntfs/super.c:1831 [inline]
 ntfs_fill_super+0x1eb6/0x76e0 fs/ntfs/super.c:2908
 mount_bdev+0x26f/0x330 fs/super.c:1134
 ntfs_mount+0x10/0x20 fs/ntfs/super.c:3065
 mount_fs+0x7f/0x269 fs/super.c:1237
 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0x352/0x2af0 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xb1/0xd0 fs/namespace.c:3072
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4607ea
RSP: 002b:00007f24df1bca88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f24df1bcb20 RCX: 00000000004607ea
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f24df1bcae0
RBP: 00007f24df1bcae0 R08: 00007f24df1bcb20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 000000002007dd00

The buggy address belongs to the page:
page:ffffea00071f5780 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x17ffe0000000000()
raw: 017ffe0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea00071f57a0 ffffea00071f57a0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c7d5e580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881c7d5e600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881c7d5e680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881c7d5e700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881c7d5e780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================