[syzbot] general protection fault in snd_rawmidi_write

[syzbot <syzbot+52d5f07074cbd0fa32d4@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0a093b2893c7 Add linux-next specific files for 20230112
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=168edb4a480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=835f3591019836d5
dashboard link: https://syzkaller.appspot.com/bug?extid=52d5f07074cbd0fa32d4
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8111a570d6cb/disk-0a093b28.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ecc135b7fc9a/vmlinux-0a093b28.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ca8d73b446ea/bzImage-0a093b28.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+52d5f07074cbd0fa32d4@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 1 PID: 8401 Comm: syz-executor.4 Not tainted 6.2.0-rc3-next-20230112-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
RIP: 0010:snd_rawmidi_ready_append sound/core/rawmidi.c:119 [inline]
RIP: 0010:snd_rawmidi_write+0x358/0xbb0 sound/core/rawmidi.c:1592
Code: f9 48 8b 44 24 38 48 c1 e8 03 80 3c 18 00 0f 85 0d 07 00 00 48 8b 04 24 4c 8b b0 a0 00 00 00 49 8d 7e 38 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 06 07 00 00 49 8d 7e 30 49 8b 6e 38 48 89 f8 48
RSP: 0018:ffffc900050a7c28 EFLAGS: 00010002

RAX: 0000000000000007 RBX: dffffc0000000000 RCX: ffffc9000e84b000
RDX: 0000000000040000 RSI: ffffffff879a3daf RDI: 0000000000000038
RBP: 0000000000001bb8 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000001bb8 R11: 0000000000000000 R12: ffff88807ac10000
R13: ffff888149ef0630 R14: 0000000000000000 R15: ffffc900050a7cc0
FS:  00007f9e6738e700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200ce000 CR3: 0000000029217000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 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: 0033:0x7f9e6668c0c9
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:00007f9e6738e168 EFLAGS: 00000246
 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9e667ac1f0 RCX: 00007f9e6668c0c9
RDX: 00000000fffffd2c RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f9e666e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffec721559f R14: 00007f9e6738e300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:snd_rawmidi_ready_append sound/core/rawmidi.c:119 [inline]
RIP: 0010:snd_rawmidi_write+0x358/0xbb0 sound/core/rawmidi.c:1592
Code: f9 48 8b 44 24 38 48 c1 e8 03 80 3c 18 00 0f 85 0d 07 00 00 48 8b 04 24 4c 8b b0 a0 00 00 00 49 8d 7e 38 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 06 07 00 00 49 8d 7e 30 49 8b 6e 38 48 89 f8 48
RSP: 0018:ffffc900050a7c28 EFLAGS: 00010002

RAX: 0000000000000007 RBX: dffffc0000000000 RCX: ffffc9000e84b000
RDX: 0000000000040000 RSI: ffffffff879a3daf RDI: 0000000000000038
RBP: 0000000000001bb8 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000001bb8 R11: 0000000000000000 R12: ffff88807ac10000
R13: ffff888149ef0630 R14: 0000000000000000 R15: ffffc900050a7cc0
FS:  00007f9e6738e700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200ce000 CR3: 0000000029217000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	f9                   	stc
   1:	48 8b 44 24 38       	mov    0x38(%rsp),%rax
   6:	48 c1 e8 03          	shr    $0x3,%rax
   a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
   e:	0f 85 0d 07 00 00    	jne    0x721
  14:	48 8b 04 24          	mov    (%rsp),%rax
  18:	4c 8b b0 a0 00 00 00 	mov    0xa0(%rax),%r14
  1f:	49 8d 7e 38          	lea    0x38(%r14),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1) <-- trapping instruction
  2e:	0f 85 06 07 00 00    	jne    0x73a
  34:	49 8d 7e 30          	lea    0x30(%r14),%rdi
  38:	49 8b 6e 38          	mov    0x38(%r14),%rbp
  3c:	48 89 f8             	mov    %rdi,%rax
  3f:	48                   	rex.W


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