bisecting fixing commit since a1b977b49b66c75e6c51a515f6700371ae720217
building syzkaller on 6e262c73cd452097096f0b4d5d96f5ae496bc021
testing commit a1b977b49b66c75e6c51a515f6700371ae720217 with gcc (GCC) 8.1.0
kernel signature: 899f95a5129e34a4a5350e3a009b8d8ba7dc933dc018f53fb6b04b91d4c8b0e2
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
testing current HEAD 13d2ce42de8cb98ff952f8de6307f896203854c2
testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 with gcc (GCC) 8.1.0
kernel signature: d2c24342022ea85921d9ba71843fecff09c069decdff59e716492d5dc9e62447
all runs: crashed: KASAN: use-after-free Read in reiserfs_fill_super
revisions tested: 2, total time: 27m8.91897188s (build: 20m26.773744075s, test: 5m59.79783119s)
the crash still happens on HEAD
commit msg: Linux 4.19.163
crash: KASAN: use-after-free Read in reiserfs_fill_super
REISERFS (device loop0): using 3.5.x disk format
REISERFS warning (device loop1): vs-13075 reiserfs_read_locked_inode: dead inode read from disk [1 2 0x0 SD]. This is likely to be race with knfsd. Ignore
REISERFS (device loop1): Using r5 hash to sort names
==================================================================
REISERFS (device loop1): using 3.5.x disk format
BUG: KASAN: use-after-free in init_inode fs/reiserfs/inode.c:1327 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x273b/0x2800 fs/reiserfs/inode.c:1576
Read of size 4 at addr ffff8881c020c000 by task syz-executor.4/7723

CPU: 1 PID: 7723 Comm: syz-executor.4 Not tainted 4.19.163-syzkaller #0
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+0x17c/0x22a lib/dump_stack.c:118
 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x307 mm/kasan/report.c:412
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:443
 init_inode fs/reiserfs/inode.c:1327 [inline]
 reiserfs_read_locked_inode+0x273b/0x2800 fs/reiserfs/inode.c:1576
 reiserfs_fill_super+0x1403/0x26b0 fs/reiserfs/super.c:2084
 mount_bdev+0x26f/0x330 fs/super.c:1158
 get_super_block+0x10/0x20 fs/reiserfs/super.c:2609
 mount_fs+0x7f/0x2a2 fs/super.c:1261
 vfs_kern_mount.part.11+0x58/0x3d0 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 do_new_mount fs/namespace.c:2469 [inline]
 do_mount+0x376/0x2710 fs/namespace.c:2799
 ksys_mount+0xba/0xe0 fs/namespace.c:3015
 __do_sys_mount fs/namespace.c:3029 [inline]
 __se_sys_mount fs/namespace.c:3026 [inline]
 __x64_sys_mount+0xb9/0x150 fs/namespace.c:3026
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4608aa
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f99095d6a88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f99095d6b20 RCX: 00000000004608aa
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f99095d6ae0
RBP: 00007f99095d6ae0 R08: 00007f99095d6b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000200 R15: 0000000020011100

The buggy address belongs to the page:
page:ffffea0007008300 count:0 mapcount:0 mapping:0000000000000000 index:0x1
REISERFS warning (device loop2): vs-13075 reiserfs_read_locked_inode: dead inode read from disk [1 2 0x0 SD]. This is likely to be race with knfsd. Ignore
flags: 0x17ffe0000000000()
raw: 017ffe0000000000 ffffea0007004548 ffff8881f672fe28 0000000000000000
REISERFS (device loop2): Using r5 hash to sort names
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c020bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881c020bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881c020c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
REISERFS (device loop2): using 3.5.x disk format
                   ^
 ffff8881c020c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
REISERFS warning (device loop5): vs-13075 reiserfs_read_locked_inode: dead inode read from disk [1 2 0x0 SD]. This is likely to be race with knfsd. Ignore
 ffff8881c020c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
REISERFS (device loop5): Using r5 hash to sort names
==================================================================
REISERFS (device loop5): using 3.5.x disk format