Dear developers and maintainers,

We encountered a general protection fault while using our modified
Syzkaller. It is tested against latest upstream Linux (6.9-rc3).
Kernel config and C repro are attached to this email. The Kernel crash
log is listed below.
```
Syzkaller hit 'general protection fault in mod_objcg_mlstate' bug.

general protection fault, probably for non-canonical address
0xdffffc00400000cb: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range
[0x0000000200000658-0x000000020000065f]
CPU: 1 PID: 8107 Comm: syz-executor203 Not tainted 6.7.0-rc7 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:754 [inline]
RIP: 0010:mod_objcg_mlstate+0xef/0x260 mm/memcontrol.c:2955
Code: 80 3c 02 00 0f 85 7f 01 00 00 4a 8b ac f5 40 0c 00 00 48 8d bd
58 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c
02 00 0f 85 41 01 00 00 48 3b 9d 58 06 00 00 0f 85 1e 01 00
RSP: 0018:ffffc900001c8ce8 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: ffff88813fff7000 RCX: 1ffff92000039167
RDX: 00000000400000cb RSI: 0000000000000101 RDI: 0000000200000659
RBP: 0000000200000001 R08: 0000000000000000 R09: fffffbfff23e8bd0
R10: ffffffff91f45e87 R11: 0000000000000000 R12: 0000000000000005
R13: 0000000000000828 R14: 0000000000000001 R15: 0000000000000000
FS:  00005555571dd3c0(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe24f656790 CR3: 000000001b539000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <IRQ>
 drain_obj_stock+0x126/0x390 mm/memcontrol.c:3438
 refill_obj_stock+0xea/0x500 mm/memcontrol.c:3487
 memcg_slab_free_hook+0x14f/0x2b0 mm/slab.h:572
 slab_free mm/slub.c:3804 [inline]
 __kmem_cache_free+0xa9/0x1a0 mm/slub.c:3822
 __d_free_external+0x43/0x60 fs/dcache.c:304
 rcu_do_batch kernel/rcu/tree.c:2158 [inline]
 rcu_core+0x817/0x1670 kernel/rcu/tree.c:2431
 __do_softirq+0x1d4/0x85e kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644
 sysvec_apic_timer_interrupt+0x99/0xb0 arch/x86/kernel/apic/apic.c:1076
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:memmove+0x28/0x1b0 arch/x86/lib/memmove_64.S:44
Code: c3 90 f3 0f 1e fa 48 89 f8 48 39 fe 7d 0f 49 89 f0 49 01 d0 49
39 f8 0f 8f b5 00 00 00 48 83 fa 20 0f 82 01 01 00 00 48 89 d1 <f3> a4
c3 48 81 fa a8 02 00 00 72 05 40 38 fe 74 47 48 83 ea 20 48
RSP: 0018:ffffc90001b9ef40 EFLAGS: 00010286
RAX: ffff8881172d8fb4 RBX: 0000000000000002 RCX: fffffffffbad8f94
RDX: ffffffffffffffe0 RSI: ffff88811b7ffff0 RDI: ffff88811b800000
RBP: 0000000000000010 R08: ffff8881172d8f84 R09: 0000766972705f73
R10: 667265736965722e R11: 0000766972705f73 R12: 0000000000000001
R13: ffff8881172d8f84 R14: ffff8881172d8fa4 R15: 0000000000000010
 leaf_paste_entries+0x442/0x910 fs/reiserfs/lbalance.c:1377
 balance_leaf_finish_node_paste_dirent fs/reiserfs/do_balan.c:1295 [inline]
 balance_leaf_finish_node_paste fs/reiserfs/do_balan.c:1321 [inline]
 balance_leaf_finish_node fs/reiserfs/do_balan.c:1364 [inline]
 balance_leaf+0x9669/0xd750 fs/reiserfs/do_balan.c:1452
 do_balance+0x318/0x810 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x637/0x7d0 fs/reiserfs/stree.c:2158
 reiserfs_add_entry+0x8ce/0xd10 fs/reiserfs/namei.c:565
 reiserfs_mkdir+0x683/0x990 fs/reiserfs/namei.c:860
 create_privroot fs/reiserfs/xattr.c:891 [inline]
 reiserfs_xattr_init+0x4e4/0xaf0 fs/reiserfs/xattr.c:1007
 reiserfs_fill_super+0x2140/0x2ea0 fs/reiserfs/super.c:2175
 mount_bdev+0x201/0x2f0 fs/super.c:1650
 legacy_get_tree+0x109/0x220 fs/fs_context.c:662
 vfs_get_tree+0x91/0x380 fs/super.c:1771
 do_new_mount fs/namespace.c:3337 [inline]
 path_mount+0x675/0x1e40 fs/namespace.c:3664
 do_mount fs/namespace.c:3677 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount fs/namespace.c:3863 [inline]
 __x64_sys_mount+0x283/0x300 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fe80d8f6c7e
Code: 48 c7 c0 ff ff ff ff eb aa e8 0e 08 00 00 66 2e 0f 1f 84 00 00
00 00 00 0f 1f 40 00 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff1ac97688 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00005555571dd378 RCX: 00007fe80d8f6c7e
RDX: 0000000020001100 RSI: 0000000020001140 RDI: 00007fff1ac976a0
RBP: 00007fff1ac976a0 R08: 00007fff1ac976e0 R09: 00000000000010e9
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000000000
R13: 00007fff1ac976e0 R14: 0000000000000003 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:754 [inline]
RIP: 0010:mod_objcg_mlstate+0xef/0x260 mm/memcontrol.c:2955
Code: 80 3c 02 00 0f 85 7f 01 00 00 4a 8b ac f5 40 0c 00 00 48 8d bd
58 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c
02 00 0f 85 41 01 00 00 48 3b 9d 58 06 00 00 0f 85 1e 01 00
RSP: 0018:ffffc900001c8ce8 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: ffff88813fff7000 RCX: 1ffff92000039167
RDX: 00000000400000cb RSI: 0000000000000101 RDI: 0000000200000659
RBP: 0000000200000001 R08: 0000000000000000 R09: fffffbfff23e8bd0
R10: ffffffff91f45e87 R11: 0000000000000000 R12: 0000000000000005
R13: 0000000000000828 R14: 0000000000000001 R15: 0000000000000000
FS:  00005555571dd3c0(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe24f656790 CR3: 000000001b539000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
----------------
Code disassembly (best guess):
   0:    80 3c 02 00              cmpb   $0x0,(%rdx,%rax,1)
   4:    0f 85 7f 01 00 00        jne    0x189
   a:    4a 8b ac f5 40 0c 00     mov    0xc40(%rbp,%r14,8),%rbp
  11:    00
  12:    48 8d bd 58 06 00 00     lea    0x658(%rbp),%rdi
  19:    48 b8 00 00 00 00 00     movabs $0xdffffc0000000000,%rax
  20:    fc ff df
  23:    48 89 fa                 mov    %rdi,%rdx
  26:    48 c1 ea 03              shr    $0x3,%rdx
* 2a:    80 3c 02 00              cmpb   $0x0,(%rdx,%rax,1) <--
trapping instruction
  2e:    0f 85 41 01 00 00        jne    0x175
  34:    48 3b 9d 58 06 00 00     cmp    0x658(%rbp),%rbx
  3b:    0f                       .byte 0xf
  3c:    85 1e                    test   %ebx,(%rsi)
  3e:    01 00                    add    %eax,(%rax)
```
We analyzed the cause of this problem. In function leaf_paste_entries
of fs/reiserfs/lbalance.c, in line 1377, while memmove dest to src,
the size n is -32, which means insert_point is before deh.
insert_point is calculated in line 1349, and deh_location of
deh[before - 1] is 0, so that insert_point equals item location. On
the other hand, deh move to 32 bytes after, which is of two struct
reiserfs_de_head.

If you have any question, please contact us.
Reported by: Yue Sun <samsun1006219@gmail.com>
Reported by: xingwei lee <xrivendell7@gmail.com>

Best Regards,
Yue