bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67
building syzkaller on 5ef9c29141f85f210b326ce68718498ae0c1fd35
testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0
kernel signature: bc32c83b4e39d157d77538bd81b4bbb76b0b96a92998432e1dfb362d4a3b6c5a
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
testing current HEAD 1752938529c614a8ed4432ecce6ebc95d3b87207
testing commit 1752938529c614a8ed4432ecce6ebc95d3b87207 with gcc (GCC) 8.1.0
kernel signature: f0a9a4e15459d6b59768e5ea6ab5d8b8aa71a370b1a2560281abe044847c5e1e
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
revisions tested: 2, total time: 23m13.422079732s (build: 17m9.304235383s, test: 5m26.362507946s)
the crash still happens on HEAD
commit msg: Linux 4.14.213
crash: KASAN: use-after-free Read in reiserfs_fill_super
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
REISERFS (device loop2): checking transaction log (loop2)
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
==================================================================
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 ffff8881c3286000 by task syz-executor.3/7235
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1

CPU: 0 PID: 7235 Comm: syz-executor.3 Not tainted 4.14.213-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
batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems!
 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
batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3e) already exists on: batadv_slave_1
 reiserfs_fill_super+0x13ea/0x26e0 fs/reiserfs/super.c:2084
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
 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:00007f36169caa88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f36169cab20 RCX: 00000000004608da
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f36169caae0
RBP: 00007f36169caae0 R08: 00007f36169cab20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020011100

The buggy address belongs to the page:
page:ffffea00070ca180 count:0 mapcount:0 mapping:          (null) index:0x1
flags: 0x17ffe0000000000()
raw: 017ffe0000000000 0000000000000000 0000000000000001 00000000ffffffff
raw: ffffea00070ca1e0 ffff8881f662eea8 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c3285f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881c3285f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881c3286000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881c3286080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881c3286100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================