Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 1 UID: 0 PID: 6650 Comm: syz.2.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:loopback_jiffies_timer_pos_update+0x13c/0x1350 sound/drivers/aloop.c:664
Code: f3 e2 f8 44 89 f8 83 e0 02 44 89 7c 24 3c 75 0a e8 79 ef e2 f8 45 31 ff eb 27 e8 6f ef e2 f8 49 8d 5d 48 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 86 6d 46 f9 4d 89 f7 4c 2b 3b 4c 89
RSP: 0018:ffffc900040af568 EFLAGS: 00010006
RAX: 0000000000000009 RBX: 0000000000000048 RCX: ffff888026d69e00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff88dbc0b0 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000ffffc9d5 R15: 0000000000000003
FS:  00007fd9569e56c0(0000) GS:ffff888126514000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 00000000766f2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 loopback_pointer+0xfb/0x1c0 sound/drivers/aloop.c:915
 snd_pcm_update_hw_ptr0+0x17a/0x1b10 sound/core/pcm_lib.c:307
 snd_pcm_update_hw_ptr sound/core/pcm_lib.c:499 [inline]
 __snd_pcm_lib_xfer+0x50e/0x1ce0 sound/core/pcm_lib.c:2326
 snd_pcm_oss_write3+0x1bc/0x320 sound/core/oss/pcm_oss.c:1241
 snd_pcm_plug_write_transfer+0x2c8/0x4c0 sound/core/oss/pcm_plugin.c:630
 snd_pcm_oss_write2 sound/core/oss/pcm_oss.c:1373 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1439 [inline]
 snd_pcm_oss_write+0xbba/0x11a0 sound/core/oss/pcm_oss.c:2795
 vfs_write+0x27b/0xb30 fs/read_write.c:684
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x8a/0x300 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fd955b8ebe9
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:00007fd9569e5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd955db5fa0 RCX: 00007fd955b8ebe9
RDX: 0000000000088020 RSI: 0000200000002000 RDI: 0000000000000003
RBP: 00007fd955c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd955db6038 R14: 00007fd955db5fa0 R15: 00007fff75956428
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:loopback_jiffies_timer_pos_update+0x13c/0x1350 sound/drivers/aloop.c:664
Code: f3 e2 f8 44 89 f8 83 e0 02 44 89 7c 24 3c 75 0a e8 79 ef e2 f8 45 31 ff eb 27 e8 6f ef e2 f8 49 8d 5d 48 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 86 6d 46 f9 4d 89 f7 4c 2b 3b 4c 89
RSP: 0018:ffffc900040af568 EFLAGS: 00010006
RAX: 0000000000000009 RBX: 0000000000000048 RCX: ffff888026d69e00
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff88dbc0b0 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000ffffc9d5 R15: 0000000000000003
FS:  00007fd9569e56c0(0000) GS:ffff888126514000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003000 CR3: 00000000766f2000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	f3 e2 f8             	repz loop 0xfffffffb
   3:	44 89 f8             	mov    %r15d,%eax
   6:	83 e0 02             	and    $0x2,%eax
   9:	44 89 7c 24 3c       	mov    %r15d,0x3c(%rsp)
   e:	75 0a                	jne    0x1a
  10:	e8 79 ef e2 f8       	call   0xf8e2ef8e
  15:	45 31 ff             	xor    %r15d,%r15d
  18:	eb 27                	jmp    0x41
  1a:	e8 6f ef e2 f8       	call   0xf8e2ef8e
  1f:	49 8d 5d 48          	lea    0x48(%r13),%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 df             	mov    %rbx,%rdi
  33:	e8 86 6d 46 f9       	call   0xf9466dbe
  38:	4d 89 f7             	mov    %r14,%r15
  3b:	4c 2b 3b             	sub    (%rbx),%r15
  3e:	4c                   	rex.WR
  3f:	89                   	.byte 0x89