bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67
building syzkaller on 5ef9c29141f85f210b326ce68718498ae0c1fd35
testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0
kernel signature: 28ee4284de8901619e1e24c510e1d63753dff1a29af30186bfd78e6f3de53835
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
testing current HEAD 2b79150141611d3c6e1b55d4e70f49602482f0b8
testing commit 2b79150141611d3c6e1b55d4e70f49602482f0b8 with gcc (GCC) 8.1.0
kernel signature: 426754448ac58fbc97db8665434a3732abac2b6a94e53ccfe38aa5333db8a6e5
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
revisions tested: 2, total time: 22m51.452647471s (build: 16m22.624500137s, test: 5m50.447350038s)
the crash still happens on HEAD
commit msg: Linux 4.14.203
crash: KASAN: use-after-free Read in reiserfs_fill_super
REISERFS (device loop5): checking transaction log (loop5)
REISERFS (device loop2): found reiserfs format "3.5" with standard journal
REISERFS (device loop2): using ordered data mode
==================================================================
reiserfs: using flush barriers
BUG: KASAN: use-after-free in init_inode fs/reiserfs/inode.c:1326 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x2443/0x27e0 fs/reiserfs/inode.c:1575
Read of size 4 at addr ffff888080b96000 by task syz-executor.0/7927

CPU: 1 PID: 7927 Comm: syz-executor.0 Not tainted 4.14.203-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
 init_inode fs/reiserfs/inode.c:1326 [inline]
 reiserfs_read_locked_inode+0x2443/0x27e0 fs/reiserfs/inode.c:1575
REISERFS (device loop2): journal params: device loop2, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
 reiserfs_fill_super+0x13ea/0x26e0 fs/reiserfs/super.c:2084
 mount_bdev+0x26f/0x330 fs/super.c:1134
 get_super_block+0x10/0x20 fs/reiserfs/super.c:2609
 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: 0033:0x4608da
RSP: 002b:00007f70892c7a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f70892c7b20 RCX: 00000000004608da
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f70892c7ae0
RBP: 00007f70892c7ae0 R08: 00007f70892c7b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020011100

The buggy address belongs to the page:
page:ffffea000202e580 count:0 mapcount:0 mapping:          (null) index:0x1
flags: 0xfffe0000000000()
raw: 00fffe0000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea000202e5e0 ffff8880ba92ed48 0000000000000000 0000000000000000
REISERFS (device loop2): checking transaction log (loop2)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888080b95f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888080b95f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888080b96000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888080b96080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888080b96100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================