[syzbot] [iommu?] general protection fault in iommufd_ioas_change_process

[syzbot <syzbot+48637757323884de77a2@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    3d6d817622b0 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10b01a9e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307
dashboard link: https://syzkaller.appspot.com/bug?extid=48637757323884de77a2
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13dbb225580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14b01a9e580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-3d6d8176.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f486efba4dfc/vmlinux-3d6d8176.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9b9dcf9ee9f3/bzImage-3d6d8176.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+48637757323884de77a2@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000018: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000000c0-0x00000000000000c7]
CPU: 2 UID: 0 PID: 6443 Comm: syz.0.201 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
RIP: 0010:iommufd_ioas_change_process+0x513/0x11c0 drivers/iommu/iommufd/ioas.c:538
Code: 5b fc 48 8d 7b 68 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 e1 0a 00 00 48 8b 6b 68 48 8d bd c0 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 74 08 3c 03 0f 8e d5 0a 00 00 8b ad c0 00 00
RSP: 0018:ffffc9000503fba0 EFLAGS: 00010206
RAX: 0000000000000018 RBX: ffff8880550e9400 RCX: ffffffff8526f53b
RDX: ffff88802c6b8000 RSI: ffffffff85af13fb RDI: 00000000000000c0
RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000001fff R11: 0000000000000000 R12: 0000000000000007
R13: fffffbfff22438f4 R14: dffffc0000000000 R15: ffffc9000503fc38
FS:  00007f1248ff36c0(0000) GS:ffff8880d5fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1248ff2ff8 CR3: 000000005355a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 iommufd_fops_ioctl+0x358/0x520 drivers/iommu/iommufd/main.c:533
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f124819e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1248ff3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1248426090 RCX: 00007f124819e0d9
RDX: 0000200000000000 RSI: 0000000000003b92 RDI: 0000000000000003
RBP: 00007f1248235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1248426128 R14: 00007f1248426090 R15: 00007ffea12de908
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:iommufd_ioas_change_process+0x513/0x11c0 drivers/iommu/iommufd/ioas.c:538
Code: 5b fc 48 8d 7b 68 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 e1 0a 00 00 48 8b 6b 68 48 8d bd c0 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 74 08 3c 03 0f 8e d5 0a 00 00 8b ad c0 00 00
RSP: 0018:ffffc9000503fba0 EFLAGS: 00010206
RAX: 0000000000000018 RBX: ffff8880550e9400 RCX: ffffffff8526f53b
RDX: ffff88802c6b8000 RSI: ffffffff85af13fb RDI: 00000000000000c0
RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000001fff R11: 0000000000000000 R12: 0000000000000007
R13: fffffbfff22438f4 R14: dffffc0000000000 R15: ffffc9000503fc38
FS:  00007f1248ff36c0(0000) GS:ffff8880d5fec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1248ff2ff8 CR3: 000000005355a000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	5b                   	pop    %rbx
   1:	fc                   	cld
   2:	48 8d 7b 68          	lea    0x68(%rbx),%rdi
   6:	48 89 f8             	mov    %rdi,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1)
  12:	0f 85 e1 0a 00 00    	jne    0xaf9
  18:	48 8b 6b 68          	mov    0x68(%rbx),%rbp
  1c:	48 8d bd c0 00 00 00 	lea    0xc0(%rbp),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 30       	movzbl (%rax,%r14,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	74 08                	je     0x3b
  33:	3c 03                	cmp    $0x3,%al
  35:	0f 8e d5 0a 00 00    	jle    0xb10
  3b:	8b                   	.byte 0x8b
  3c:	ad                   	lods   %ds:(%rsi),%eax
  3d:	c0 00 00             	rolb   $0x0,(%rax)


---
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