Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 9777 Comm: syz.2.777 Not tainted 6.16.0-rc3-next-20250623-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:pidfs_free_pid+0xaf/0x140 fs/pidfs.c:162
Code: f0 ff ff 73 e4 43 80 3c 3c 00 74 08 4c 89 f7 e8 a7 1b de ff 49 83 3e 00 0f 85 84 00 00 00 e8 08 f2 79 ff 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 82 1b de ff 4c 8b 33 4d 85 f6 74
RSP: 0018:ffffc90000007b90 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888020735a00
RDX: 0000000000000100 RSI: 0000000000000001 RDI: ffff8880755d6df0
RBP: 0000000000000001 R08: ffff8880755d6d83 R09: 1ffff1100eabadb0
R10: dffffc0000000000 R11: ffffed100eabadb1 R12: 1ffff1100eabadbd
R13: ffffffff81a83684 R14: ffff8880755d6de8 R15: dffffc0000000000
FS:  00007f21265536c0(0000) GS:ffff888125c25000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f19f8b7e2d8 CR3: 000000007541c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 put_pid+0x9c/0x130 kernel/pid.c:103
 rcu_do_batch kernel/rcu/tree.c:2582 [inline]
 rcu_core+0xca5/0x1710 kernel/rcu/tree.c:2838
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_release+0x2b5/0x3e0 kernel/locking/lockdep.c:5896
Code: 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b 05 7b f1 01 11 <48> 3b 44 24 28 0f 85 8b 00 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc9000cf67558 EFLAGS: 00000206
RAX: 984451f41a69c000 RBX: 0000000000000202 RCX: 984451f41a69c000
RDX: 0000000000000000 RSI: ffffffff8db7f137 RDI: ffffffff8be322c0
RBP: ffff8880207364f0 R08: ffff888077bf5d67 R09: 1ffff1100ef7ebac
R10: dffffc0000000000 R11: ffffed100ef7ebad R12: 0000000000000000
R13: 0000000000000000 R14: ffff88807a70c7d8 R15: ffff888020735a00
 __mutex_unlock_slowpath+0xc7/0x700 kernel/locking/mutex.c:909
 __unix_dgram_recvmsg+0xa2f/0xde0 net/unix/af_unix.c:2584
 sock_recvmsg_nosec+0x186/0x1c0 net/socket.c:1063
 ____sys_recvmsg+0x3aa/0x460 net/socket.c:2830
 ___sys_recvmsg+0x1b5/0x510 net/socket.c:2874
 do_recvmmsg+0x307/0x770 net/socket.c:2969
 __sys_recvmmsg net/socket.c:3043 [inline]
 __do_sys_recvmmsg net/socket.c:3066 [inline]
 __se_sys_recvmmsg net/socket.c:3059 [inline]
 __x64_sys_recvmmsg+0x190/0x240 net/socket.c:3059
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f212578e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2126553038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f21259b6080 RCX: 00007f212578e929
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f2125810b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f21259b6080 R15: 00007ffc2fcbd338
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pidfs_free_pid+0xaf/0x140 fs/pidfs.c:162
Code: f0 ff ff 73 e4 43 80 3c 3c 00 74 08 4c 89 f7 e8 a7 1b de ff 49 83 3e 00 0f 85 84 00 00 00 e8 08 f2 79 ff 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 82 1b de ff 4c 8b 33 4d 85 f6 74
RSP: 0018:ffffc90000007b90 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888020735a00
RDX: 0000000000000100 RSI: 0000000000000001 RDI: ffff8880755d6df0
RBP: 0000000000000001 R08: ffff8880755d6d83 R09: 1ffff1100eabadb0
R10: dffffc0000000000 R11: ffffed100eabadb1 R12: 1ffff1100eabadbd
R13: ffffffff81a83684 R14: ffff8880755d6de8 R15: dffffc0000000000
FS:  00007f21265536c0(0000) GS:ffff888125c25000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f19f8b7e2d8 CR3: 000000007541c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	f0 ff                	lock (bad)
   2:	ff 73 e4             	push   -0x1c(%rbx)
   5:	43 80 3c 3c 00       	cmpb   $0x0,(%r12,%r15,1)
   a:	74 08                	je     0x14
   c:	4c 89 f7             	mov    %r14,%rdi
   f:	e8 a7 1b de ff       	call   0xffde1bbb
  14:	49 83 3e 00          	cmpq   $0x0,(%r14)
  18:	0f 85 84 00 00 00    	jne    0xa2
  1e:	e8 08 f2 79 ff       	call   0xff79f22b
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 82 1b de ff       	call   0xffde1bbb
  39:	4c 8b 33             	mov    (%rbx),%r14
  3c:	4d 85 f6             	test   %r14,%r14
  3f:	74                   	.byte 0x74