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

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Message-Id: <20250807081051.2253962-1-namcao@linutronix.de>
Date: Thu,  7 Aug 2025 10:10:51 +0200
From: Nam Cao <namcao@...utronix.de>
To: Nirmal Patel <nirmal.patel@...ux.intel.com>,
	Jonathan Derrick <jonathan.derrick@...ux.dev>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...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
Cc: Nam Cao <namcao@...utronix.de>,
	Kenneth Crudup <kenny@...ix.com>,
	Ammar Faizi <ammarfaizi2@...weeb.org>
Subject: [PATCH v2] PCI: vmd: Fix wrong kfree() in vmd_msi_free()

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>
---
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