RE: [PATCH] iommu/vt-d: Fix oops due to out of scope access

[Duan, Zhenzhong]

>-----Original Message-----
>From: Tian, Kevin <kevin.tian@xxxxxxxxx>
>Subject: RE: [PATCH] iommu/vt-d: Fix oops due to out of scope access
>
>> From: Duan, Zhenzhong <zhenzhong.duan@xxxxxxxxx>
>> Sent: Tuesday, April 21, 2026 11:14 AM
>>
>> Below oops triggers when kill QEMU process:
>>
>>   Oops: general protection fault, probably for non-canonical address
>> 0x7fffffff844eaaa7: 0000 [#1] SMP NOPTI
>>   Call Trace:
>>    <TASK>
>>    do_raw_spin_lock+0xaa/0xc0
>>    _raw_spin_lock_irqsave+0x21/0x40
>>    domain_remove_dev_pasid+0x52/0x160
>>    intel_nested_set_dev_pasid+0x1b9/0x1e0
>>    __iommu_set_group_pasid+0x56/0x120
>>    pci_dev_reset_iommu_done+0xe3/0x180
>>    pcie_flr+0x65/0x160
>>    __pci_reset_function_locked+0x5b/0x120
>>    vfio_pci_core_close_device+0x63/0xe0 [vfio_pci_core]
>>    vfio_df_close+0x4f/0xa0
>>    vfio_df_unbind_iommufd+0x2d/0x60
>>    vfio_device_fops_release+0x3e/0x40
>>    __fput+0xe5/0x2c0
>>    task_work_run+0x58/0xa0
>>    do_exit+0x2c8/0x600
>>    do_group_exit+0x2f/0xa0
>>    get_signal+0x863/0x8c0
>>    arch_do_signal_or_restart+0x24/0x100
>>    exit_to_user_mode_loop+0x87/0x380
>>    do_syscall_64+0x2ff/0x11e0
>>    entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> The global static blocked domain is a dummy domain without corresponding
>> dmar_domain structure, accessing beyond iommu_domain structure triggers
>> oops easily. Fix it by return early in domain_remove_dev_pasid() like
>> identity domain.
>
>It's interesting why this doesn't hurt us in normal attach/detach paths...

IIUC, other call path never pass in blocked domain as old domain.

>
>>
>> Fixes: 7d0c9da6c150 ("iommu/vt-d: Add set_dev_pasid callback for dma
>> domain")
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
>
>Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
>
>btw Sashiko captured another issue in existing code. Could you help fix it too?

Will do.

Thanks
Zhenzhong

>
>https://sashiko.dev/#/patchset/20260421031347.1408890-1-
>zhenzhong.duan%40intel.com