linux-kernel - Re: [PATCH v2] PCI: vmd: Fix wrong kfree() in vmd_msi

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Message-ID: <rbwjykknpgx5hgu36t7ncxbs6kpq4a6ty2234velg5kt7ntq4v@5jkqysy62rch>
Date: Thu, 7 Aug 2025 14:09:43 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Nam Cao <namcao@...utronix.de>
Cc: Nirmal Patel <nirmal.patel@...ux.intel.com>, 
	Jonathan Derrick <jonathan.derrick@...ux.dev>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kwilczynski@...nel.org>, Rob Herring <robh@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, linux-pci@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Kenneth Crudup <kenny@...ix.com>, 
	Ammar Faizi <ammarfaizi2@...weeb.org>
Subject: Re: [PATCH v2] PCI: vmd: Fix wrong kfree() in vmd_msi_free()

On Thu, Aug 07, 2025 at 10:10:51AM GMT, Nam Cao wrote:
> vmd_msi_alloc() allocates struct vmd_irq and stashes it into
> irq_data->chip_data associated with the VMD's interrupt domain.
> vmd_msi_free() extracts the pointer by calling irq_get_chip_data() and
> frees it.
> 
> irq_get_chip_data() returns the chip_data associated with the top interrupt
> domain. This worked in the past, because VMD's interrupt domain was the top
> domain.
> 
> But since commit d7d8ab87e3e7 ("PCI: vmd: Switch to
> msi_create_parent_irq_domain()") changed the interrupt domain hierarchy,
> VMD's interrupt domain is not the top domain anymore. irq_get_chip_data()
> now returns the chip_data at the MSI devices' interrupt domains. It is
> therefore broken for vmd_msi_free() to kfree() this chip_data.
> 
> Fix this issue, correctly extract the chip_data associated with the VMD's
> interrupt domain.
> 
> Fixes: d7d8ab87e3e7 ("PCI: vmd: Switch to msi_create_parent_irq_domain()")
> Reported-by: Kenneth Crudup <kenny@...ix.com>
> Closes: https://lore.kernel.org/linux-pci/dfa40e48-8840-4e61-9fda-25cdb3ad81c1@panix.com/
> Reported-by: Ammar Faizi <ammarfaizi2@...weeb.org>
> Closes: https://lore.kernel.org/linux-pci/ed53280ed15d1140700b96cca2734bf327ee92539e5eb68e80f5bbbf0f01@linux.gnuweeb.org/
> Tested-by: Ammar Faizi <ammarfaizi2@...weeb.org>
> Tested-by: Kenneth Crudup <kenny@...ix.com>
> Signed-off-by: Nam Cao <namcao@...utronix.de>

Acked-by: Manivannan Sadhasivam <mani@...nel.org>

- Mani

> ---
> v2: Fix typo and describe the change more precisely
> ---
>  drivers/pci/controller/vmd.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index 9bbb0ff4cc15..b679c7f28f51 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -280,10 +280,12 @@ static int vmd_msi_alloc(struct irq_domain *domain, unsigned int virq,
>  static void vmd_msi_free(struct irq_domain *domain, unsigned int virq,
>  			 unsigned int nr_irqs)
>  {
> +	struct irq_data *irq_data;
>  	struct vmd_irq *vmdirq;
>  
>  	for (int i = 0; i < nr_irqs; ++i) {
> -		vmdirq = irq_get_chip_data(virq + i);
> +		irq_data = irq_domain_get_irq_data(domain, virq + i);
> +		vmdirq = irq_data->chip_data;
>  
>  		synchronize_srcu(&vmdirq->irq->srcu);
>  
> -- 
> 2.39.5
> 

-- 
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