linux-kernel - Re: [PATCH 6.6.y] iommu/amd: Fixes refcount bug in iommu

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Message-ID: <2025030602-trowel-cartridge-fbf0@gregkh>
Date: Thu, 6 Mar 2025 08:01:10 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Siddharth Chintamaneni <sidchintamaneni@...il.com>
Cc: stable@...r.kernel.org, joro@...tes.org, suravee.suthikulpanit@....com,
	will@...nel.org, robin.murphy@....com, iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org, wei.huang2@....com,
	apais@...rosoft.com
Subject: Re: [PATCH 6.6.y] iommu/amd: Fixes refcount bug in iommu_v2 driver

On Thu, Mar 06, 2025 at 05:18:22AM +0000, Siddharth Chintamaneni wrote:
> This fix addresses a refcount bug where the reference count was not
> properly decremented due to the mmput function not being called when
> mmu_notifier_register fails.
> 
> Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@...il.com>
> ---
>  drivers/iommu/amd/iommu_v2.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/amd/iommu_v2.c b/drivers/iommu/amd/iommu_v2.c
> index 57c2fb1146e2..bce21e266d64 100644
> --- a/drivers/iommu/amd/iommu_v2.c
> +++ b/drivers/iommu/amd/iommu_v2.c
> @@ -645,7 +645,7 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, u32 pasid,
>  
>  	ret = mmu_notifier_register(&pasid_state->mn, mm);
>  	if (ret)
> -		goto out_free;
> +		goto out_mmput;
>  
>  	ret = set_pasid_state(dev_state, pasid_state, pasid);
>  	if (ret)
> @@ -673,6 +673,8 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, u32 pasid,
>  
>  out_unregister:
>  	mmu_notifier_unregister(&pasid_state->mn, mm);
> +
> +out_mmput:
>  	mmput(mm);
>  
>  out_free:
> -- 
> 2.43.0
> 
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>