BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 147a5067 P4D 147a5067 PUD 5b216067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4239 Comm: kworker/u4:9 Not tainted 5.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000007d40 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000100 RCX: ffffffff815fa273
RDX: ffff88806c634ec0 RSI: ffffffff815f9f0f RDI: ffff8880190d9810
RBP: ffffc90000007d80 R08: 0000000000000000 R09: ffffffff8cecd64f
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880190d9810
R13: 1ffff92000000faa R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000147a4000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1410
 expire_timers kernel/time/timer.c:1455 [inline]
 __run_timers.part.0+0x67c/0xa50 kernel/time/timer.c:1747
 __run_timers kernel/time/timer.c:1728 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1760
 __do_softirq+0x2a0/0x9f6 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:393 [inline]
 __irq_exit_rcu kernel/softirq.c:423 [inline]
 irq_exit_rcu+0x132/0x200 kernel/softirq.c:435
 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x9/0x60 kernel/kcov.c:197
Code: 8b 48 89 54 24 08 48 89 34 24 e8 72 3c 5f 02 48 8b 54 24 08 48 8b 34 24 e9 a1 fd ff ff 0f 1f 40 00 65 48 8b 14 25 00 f0 01 00 <65> 8b 05 10 eb 91 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74
RSP: 0018:ffffc9000207fde8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88806c634ec0 RCX: ffffffff81421f61
RDX: ffff88806c634ec0 RSI: ffff88806c634ec0 RDI: 0000000000000007
RBP: ffffc90002079ac0 R08: 0000000000000000 R09: ffff88801ed96407
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90002078000 R14: dffffc0000000000 R15: ffff88806c635418
 stack_not_used include/linux/sched/task_stack.h:99 [inline]
 check_stack_usage kernel/exit.c:695 [inline]
 do_exit+0x17fd/0x29b0 kernel/exit.c:852
 call_usermodehelper_exec_async+0x413/0x580 kernel/umh.c:123
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
CR2: 0000000000000000
---[ end trace 053d70e9c2aa465a ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc90000007d40 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000100 RCX: ffffffff815fa273
RDX: ffff88806c634ec0 RSI: ffffffff815f9f0f RDI: ffff8880190d9810
RBP: ffffc90000007d80 R08: 0000000000000000 R09: ffffffff8cecd64f
R10: 0000000000000000 R11: 0000000000000001 R12: ffff8880190d9810
R13: 1ffff92000000faa R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000147a4000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400