ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 1482 Comm: kworker/1:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events vidtv_mux_tick
RIP: 0010:vidtv_s302m_encode+0x269/0x1860 drivers/media/test-drivers/vidtv/vidtv_s302m.c:414
Code: fd ab f9 31 ff 89 de e8 35 f7 ab f9 84 db 0f 85 37 0d 00 00 e8 18 fd ab f9 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e e7 14 00 00 48 8b 44 24 08 41
RSP: 0000:ffffc90007acf830 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000400
RDX: 0000000000000000 RSI: ffffffff885daf48 RDI: ffff88801bc428c0
RBP: 0000000000000000 R08: 0000000000000dc0 R09: 00000000ffffffff
R10: ffffffff8eded4b3 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880295cd700 R15: ffff88802141f000
FS:  0000000000000000(0000) GS:ffff888096ce3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f7288950 CR3: 000000006e5a4000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 vidtv_mux_poll_encoders drivers/media/test-drivers/vidtv/vidtv_mux.c:339 [inline]
 vidtv_mux_tick+0x4e4/0x1460 drivers/media/test-drivers/vidtv/vidtv_mux.c:416
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vidtv_s302m_encode+0x269/0x1860 drivers/media/test-drivers/vidtv/vidtv_s302m.c:414
Code: fd ab f9 31 ff 89 de e8 35 f7 ab f9 84 db 0f 85 37 0d 00 00 e8 18 fd ab f9 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e e7 14 00 00 48 8b 44 24 08 41
RSP: 0000:ffffc90007acf830 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000400
RDX: 0000000000000000 RSI: ffffffff885daf48 RDI: ffff88801bc428c0
RBP: 0000000000000000 R08: 0000000000000dc0 R09: 00000000ffffffff
R10: ffffffff8eded4b3 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880295cd700 R15: ffff88802141f000
FS:  0000000000000000(0000) GS:ffff888096ce3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055594e72c354 CR3: 000000000e994000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	fd                   	std
   1:	ab                   	stos   %eax,%es:(%rdi)
   2:	f9                   	stc
   3:	31 ff                	xor    %edi,%edi
   5:	89 de                	mov    %ebx,%esi
   7:	e8 35 f7 ab f9       	call   0xf9abf741
   c:	84 db                	test   %bl,%bl
   e:	0f 85 37 0d 00 00    	jne    0xd4b
  14:	e8 18 fd ab f9       	call   0xf9abfd31
  19:	4c 89 e2             	mov    %r12,%rdx
  1c:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  23:	fc ff df
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e e7 14 00 00    	jle    0x1521
  3a:	48 8b 44 24 08       	mov    0x8(%rsp),%rax
  3f:	41                   	rex.B