Oops: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 0 UID: 0 PID: 839 Comm: syz.7.8270 Not tainted 6.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:proc_scheduler+0xc6/0x3c0 net/mptcp/ctrl.c:125
Code: 03 42 80 3c 38 00 0f 85 fe 02 00 00 4d 8b a4 24 08 09 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d 7c 24 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 cc 02 00 00 4d 8b 7c 24 28 48 8d 84 24 c8 00 00
RSP: 0018:ffffc9000c10f708 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 1ffff92001821ee2 RCX: ffffc9000c10f840
RDX: 0000000000000005 RSI: ffffffff8b08f91e RDI: 0000000000000028
RBP: 0000000000000001 R08: ffffc9000c10f930 R09: 0000000000000040
R10: 0000000000000040 R11: 0000000000003037 R12: 0000000000000000
R13: ffffc9000c10f840 R14: ffffc9000c10f930 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000561183d35d98 CR3: 00000000757ae000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 proc_sys_call_handler+0x403/0x5d0 fs/proc/proc_sysctl.c:601
 __kernel_write_iter+0x318/0xa80 fs/read_write.c:612
 __kernel_write+0xf6/0x140 fs/read_write.c:632
 do_acct_process+0xcb0/0x14a0 kernel/acct.c:539
 acct_pin_kill+0x2d/0x100 kernel/acct.c:192
 pin_kill+0x194/0x7c0 fs/fs_pin.c:44
 mnt_pin_kill+0x61/0x1e0 fs/fs_pin.c:81
 cleanup_mnt+0x3ac/0x450 fs/namespace.c:1366
 task_work_run+0x14e/0x250 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0xad8/0x2d70 kernel/exit.c:938
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4525d85d29
Code: Unable to access opcode bytes at 0x7f4525d85cff.
RSP: 002b:00007ffc97f56658 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4525d85d29
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc97f566ac R08: 00007ffc97f5673f R09: 00000000000f7616
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000032
R13: 00000000000f7616 R14: 00007ffc97f56700 R15: 00007ffc97f56700
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:proc_scheduler+0xc6/0x3c0 net/mptcp/ctrl.c:125
Code: 03 42 80 3c 38 00 0f 85 fe 02 00 00 4d 8b a4 24 08 09 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d 7c 24 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 cc 02 00 00 4d 8b 7c 24 28 48 8d 84 24 c8 00 00
RSP: 0018:ffffc9000c10f708 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 1ffff92001821ee2 RCX: ffffc9000c10f840
RDX: 0000000000000005 RSI: ffffffff8b08f91e RDI: 0000000000000028
RBP: 0000000000000001 R08: ffffc9000c10f930 R09: 0000000000000040
R10: 0000000000000040 R11: 0000000000003037 R12: 0000000000000000
R13: ffffc9000c10f840 R14: ffffc9000c10f930 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbd79a91dd0 CR3: 00000000757ae000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1)
   5:	0f 85 fe 02 00 00    	jne    0x309
   b:	4d 8b a4 24 08 09 00 	mov    0x908(%r12),%r12
  12:	00
  13:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1a:	fc ff df
  1d:	49 8d 7c 24 28       	lea    0x28(%r12),%rdi
  22:	48 89 fa             	mov    %rdi,%rdx
  25:	48 c1 ea 03          	shr    $0x3,%rdx
* 29:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2d:	0f 85 cc 02 00 00    	jne    0x2ff
  33:	4d 8b 7c 24 28       	mov    0x28(%r12),%r15
  38:	48                   	rex.W
  39:	8d                   	.byte 0x8d
  3a:	84 24 c8             	test   %ah,(%rax,%rcx,8)