Re: [PATCH v5 4/5] iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The global pointer `hv_iommu_device` is left pointing to freed memory on initialization error paths.
--

commit cabf0b0a28725bbdf8a09d64a7c284187b9174dc
Author: Yu Zhang <zhangyu1@linux.microsoft.com>

iommu/hyperv: Add para-virtualized IOMMU support for Hyper-V guest

This commit introduces a para-virtualized IOMMU driver for Linux guests on
Hyper-V. It implements stage-1 IO translation within the guest OS by utilizing
Hyper-V hypercalls.

> diff --git a/drivers/iommu/hyperv/hv-iommu-guest.c b/drivers/iommu/hyperv/hv-iommu-guest.c
> new file mode 100644
> index 0000000000000..137f232d74fe5
> --- /dev/null
> +++ b/drivers/iommu/hyperv/hv-iommu-guest.c
[ ... ]
> +static void __init
> +hv_init_iommu_device(struct hv_iommu_dev *hv_iommu,
> +		     struct hv_output_get_iommu_capabilities *hv_iommu_cap)
> +{
[ ... ]
> +	hv_iommu_device = hv_iommu;
> +}
> +
> +int __init hv_iommu_init(void)
> +{
[ ... ]
> +	hv_iommu = kzalloc_obj(*hv_iommu, GFP_KERNEL);
> +	if (!hv_iommu)
> +		return -ENOMEM;
> +
> +	hv_init_iommu_device(hv_iommu, &hv_iommu_cap);
> +
> +	ret = hv_initialize_static_domains();
> +	if (ret)
> +		goto err_free;
[ ... ]
> +err_free:
> +	kfree(hv_iommu);

[Severity: Low]
If hv_iommu_init() fails after calling hv_init_iommu_device(), the allocated
memory is freed here on the err_free path. Does the global pointer
hv_iommu_device need to be reset to NULL to avoid leaving a dangling pointer?

While this might currently be unreachable because functions using
hv_iommu_device are invoked via callbacks that are only registered on
successful init, could this pose a regression risk for future code accessing
this global state?

> +	return ret;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260904075512.174154-1-zhangyu1@linux.microsoft.com?part=4