bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67
building syzkaller on 1b88c6d5c8477f1d4fb3b389443b200acc32e9a8
testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0
kernel signature: 1c3514fc6550100fb243abec6c8f1601716262b53c3f0671c2f594b5d40b2998
all runs: crashed: KASAN: use-after-free Read in ntfs_are_names_equal
testing current HEAD 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae
testing commit 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae with gcc (GCC) 8.1.0
kernel signature: d370b46661a6f7e5407f158d3a5695ff1f2742cf08a680bfddacdb0a6cdbd590
all runs: crashed: KASAN: use-after-free Read in ntfs_are_names_equal
revisions tested: 2, total time: 23m12.042593594s (build: 17m18.134193594s, test: 5m8.595574285s)
the crash still happens on HEAD
commit msg: Linux 4.14.212
crash: KASAN: use-after-free Read in ntfs_are_names_equal
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
ntfs: volume version 3.1.
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
==================================================================
BUG: KASAN: use-after-free in ntfs_ucsncmp fs/ntfs/unistr.c:156 [inline]
BUG: KASAN: use-after-free in ntfs_are_names_equal+0x178/0x1a0 fs/ntfs/unistr.c:75
Read of size 2 at addr ffff8881c7f75ee8 by task syz-executor.3/7320

CPU: 0 PID: 7320 Comm: syz-executor.3 Not tainted 4.14.212-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_load2_noabort+0x14/0x20 mm/kasan/report.c:428
 ntfs_ucsncmp fs/ntfs/unistr.c:156 [inline]
 ntfs_are_names_equal+0x178/0x1a0 fs/ntfs/unistr.c:75
 ntfs_attr_find+0x36c/0xb60 fs/ntfs/attrib.c:628
 ntfs_external_attr_find fs/ntfs/attrib.c:1107 [inline]
 ntfs_attr_lookup+0x1085/0x2480 fs/ntfs/attrib.c:1205
 ntfs_read_locked_attr_inode fs/ntfs/inode.c:1266 [inline]
 ntfs_attr_iget+0x742/0x23c0 fs/ntfs/inode.c:251
 ntfs_read_locked_inode+0x25c1/0x51d0 fs/ntfs/inode.c:986
 ntfs_iget+0xda/0x110 fs/ntfs/inode.c:190
 load_system_files fs/ntfs/super.c:1988 [inline]
 ntfs_fill_super+0x4c20/0x76e0 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:00007fa376107a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fa376107b20 RCX: 00000000004607ea
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fa376107ae0
RBP: 00007fa376107ae0 R08: 00007fa376107b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 000000002007dc00

The buggy address belongs to the page:
page:ffffea00071fdd40 count:0 mapcount:-127 mapping:          (null) index:0x1
flags: 0x17ffe0000000000()
raw: 017ffe0000000000 0000000000000000 0000000000000001 00000000ffffff80
raw: ffffea00071fe960 ffffea00071f88e0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c7f75d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881c7f75e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881c7f75e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                          ^
 ffff8881c7f75f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881c7f75f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!