syzbot

RBP: 00007ffdd1a89780 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f2508215fac R14: 00007f2508215fa0 R15: 00007f2508215fa0
 </TASK>
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 1 UID: 0 PID: 374 Comm: syz.2.20 Not tainted syzkaller #0 4cdc09a83674403ae09eb79c4caea2b8730b48e4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:cgroup_mkdir+0x117f/0x1570 kernel/cgroup/cgroup.c:5940
Code: eb 05 e8 34 4e 08 00 4c 89 ef e8 0c 9e 00 00 49 81 fd 01 f0 ff ff 0f 83 b3 fb ff ff 4d 8d b5 08 01 00 00 4c 89 f3 48 c1 eb 03 <42> 80 3c 3b 00 74 08 4c 89 f7 e8 d2 7a 60 00 49 8b bd 08 01 00 00
RSP: 0018:ffffc9000103fc88 EFLAGS: 00010206
RAX: ac696d47635aa800 RBX: 0000000000000021 RCX: ffff8881f6f3ae40
RDX: ffff88810cf38080 RSI: ffff88811604c000 RDI: ffff888100042000
RBP: ffffc9000103fd30 R08: ffffffff81db93c8 R09: ffffffff81dfa22f
R10: ffffffff81dfce3a R11: ffffffff81df9d4e R12: ffff8881281135b0
R13: 0000000000000000 R14: 0000000000000108 R15: dffffc0000000000
FS:  0000555592cdd500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 0000000115f4c000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 kernfs_iop_mkdir+0x1c2/0x2d0 fs/kernfs/dir.c:1246
 vfs_mkdir+0x582/0x820 fs/namei.c:4265
 do_mkdirat+0x240/0x530 fs/namei.c:4288
 __do_sys_mkdirat fs/namei.c:4303 [inline]
 __se_sys_mkdirat fs/namei.c:4301 [inline]
 __x64_sys_mkdirat+0x8b/0xa0 fs/namei.c:4301
 x64_sys_call+0x2ba8/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f2507f9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdd1a89718 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f2508215fa0 RCX: 00007f2507f9c799
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007ffdd1a89780 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f2508215fac R14: 00007f2508215fa0 R15: 00007f2508215fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:cgroup_mkdir+0x117f/0x1570 kernel/cgroup/cgroup.c:5940
Code: eb 05 e8 34 4e 08 00 4c 89 ef e8 0c 9e 00 00 49 81 fd 01 f0 ff ff 0f 83 b3 fb ff ff 4d 8d b5 08 01 00 00 4c 89 f3 48 c1 eb 03 <42> 80 3c 3b 00 74 08 4c 89 f7 e8 d2 7a 60 00 49 8b bd 08 01 00 00
RSP: 0018:ffffc9000103fc88 EFLAGS: 00010206
RAX: ac696d47635aa800 RBX: 0000000000000021 RCX: ffff8881f6f3ae40
RDX: ffff88810cf38080 RSI: ffff88811604c000 RDI: ffff888100042000
RBP: ffffc9000103fd30 R08: ffffffff81db93c8 R09: ffffffff81dfa22f
R10: ffffffff81dfce3a R11: ffffffff81df9d4e R12: ffff8881281135b0
R13: 0000000000000000 R14: 0000000000000108 R15: dffffc0000000000
FS:  0000555592cdd500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 0000000115f4c000 CR4: 00000000003526b0
----------------
Code disassembly (best guess):
   0:	eb 05                	jmp    0x7
   2:	e8 34 4e 08 00       	call   0x84e3b
   7:	4c 89 ef             	mov    %r13,%rdi
   a:	e8 0c 9e 00 00       	call   0x9e1b
   f:	49 81 fd 01 f0 ff ff 	cmp    $0xfffffffffffff001,%r13
  16:	0f 83 b3 fb ff ff    	jae    0xfffffbcf
  1c:	4d 8d b5 08 01 00 00 	lea    0x108(%r13),%r14
  23:	4c 89 f3             	mov    %r14,%rbx
  26:	48 c1 eb 03          	shr    $0x3,%rbx
* 2a:	42 80 3c 3b 00       	cmpb   $0x0,(%rbx,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 d2 7a 60 00       	call   0x607b0b
  39:	49 8b bd 08 01 00 00 	mov    0x108(%r13),%rdi