==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: null-ptr-deref in page_ref_count include/linux/page_ref.h:67 [inline]
BUG: KASAN: null-ptr-deref in folio_ref_count include/linux/page_ref.h:89 [inline]
BUG: KASAN: null-ptr-deref in folio_get include/linux/mm.h:1167 [inline]
BUG: KASAN: null-ptr-deref in hugetlb_fault+0x1423/0x23f0 mm/hugetlb.c:6112
Read of size 4 at addr 0000000000000034 by task syz-executor.2/17926

CPU: 1 PID: 17926 Comm: syz-executor.2 Not tainted 6.2.0-rc5-next-20230123-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 kasan_report+0xc0/0xf0 mm/kasan/report.c:517
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x141/0x190 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 page_ref_count include/linux/page_ref.h:67 [inline]
 folio_ref_count include/linux/page_ref.h:89 [inline]
 folio_get include/linux/mm.h:1167 [inline]
 hugetlb_fault+0x1423/0x23f0 mm/hugetlb.c:6112
 handle_mm_fault+0x753/0x850 mm/memory.c:5196
 do_user_addr_fault+0x475/0x1210 arch/x86/mm/fault.c:1407
 handle_page_fault arch/x86/mm/fault.c:1498 [inline]
 exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1554
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:copy_user_enhanced_fast_string+0xe/0x40 arch/x86/lib/copy_user_64.S:166
Code: d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 2c 66 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 0f 01 cb 83 fa 40 72 34 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 06 66 0f 1f 44 00 00 83 f8 12 74
RSP: 0018:ffffc90003c0fb58 EFLAGS: 00050206
RAX: 0000000000000001 RBX: 0000000000001000 RCX: 0000000000001000
RDX: 0000000000001000 RSI: 00000000204dd000 RDI: ffff888040200000
RBP: ffff888040200000 R08: 0000000000000001 R09: ffff888040200fff
R10: ffffed10080401ff R11: 0000000000000000 R12: 00007fffffffe000
R13: 00000000204dd000 R14: dffffc0000000000 R15: 00000000204dd000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0x13b/0x170 lib/usercopy.c:16
 copy_from_user include/linux/uaccess.h:161 [inline]
 snd_rawmidi_kernel_write1+0x366/0x870 sound/core/rawmidi.c:1547
 snd_rawmidi_write+0x277/0xbb0 sound/core/rawmidi.c:1616
 vfs_write+0x2db/0xe10 fs/read_write.c:582
 ksys_write+0x1ec/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc92608c0c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc926db7168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc9261ac050 RCX: 00007fc92608c0c9
RDX: 00000000fffffd2c RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007fc9260e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe5a35b6af R14: 00007fc926db7300 R15: 0000000000022000
 </TASK>
==================================================================
----------------
Code disassembly (best guess):
   0:	d1 f3                	shl    %ebx
   2:	a4                   	movsb  %ds:(%rsi),%es:(%rdi)
   3:	31 c0                	xor    %eax,%eax
   5:	0f 01 ca             	clac
   8:	c3                   	retq
   9:	8d 0c ca             	lea    (%rdx,%rcx,8),%ecx
   c:	89 ca                	mov    %ecx,%edx
   e:	eb 2c                	jmp    0x3c
  10:	66 66 2e 0f 1f 84 00 	data16 nopw %cs:0x0(%rax,%rax,1)
  17:	00 00 00 00
  1b:	90                   	nop
  1c:	f3 0f 1e fa          	endbr64
  20:	0f 01 cb             	stac
  23:	83 fa 40             	cmp    $0x40,%edx
  26:	72 34                	jb     0x5c
  28:	89 d1                	mov    %edx,%ecx
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	31 c0                	xor    %eax,%eax
  2e:	0f 01 ca             	clac
  31:	c3                   	retq
  32:	89 ca                	mov    %ecx,%edx
  34:	eb 06                	jmp    0x3c
  36:	66 0f 1f 44 00 00    	nopw   0x0(%rax,%rax,1)
  3c:	83 f8 12             	cmp    $0x12,%eax
  3f:	74                   	.byte 0x74