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Subject[PATCH] PCI/MSI: Prevent UAF in error path
Date
When the core MSI allocation fails, then the PCI/MSI code uses an already
freed MSI descriptor to unmask the MSI mask register in order to bring it back
into reset state.

Remove MSI_FLAG_FREE_MSI_DESCS from the PCI/MSI irqdomain flags and let the
PCI/MSI code free the MSI descriptors after usage.

Fixes: 0f62d941acf9 ("genirq/msi: Provide msi_domain_alloc/free_irqs_descs_locked()")
Reported-by: Tong Zhang <ztong0001@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/pci/msi/irqdomain.c | 4 ++--
drivers/pci/msi/legacy.c | 1 -
2 files changed, 2 insertions(+), 3 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -28,6 +28,7 @@ void pci_msi_teardown_msi_irqs(struct pc
msi_domain_free_irqs_descs_locked(domain, &dev->dev);
else
pci_msi_legacy_teardown_msi_irqs(dev);
+ msi_free_msi_descs(&dev->dev);
}

/**
@@ -171,8 +172,7 @@ struct irq_domain *pci_msi_create_irq_do
if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
pci_msi_domain_update_chip_ops(info);

- info->flags |= MSI_FLAG_ACTIVATE_EARLY | MSI_FLAG_DEV_SYSFS |
- MSI_FLAG_FREE_MSI_DESCS;
+ info->flags |= MSI_FLAG_ACTIVATE_EARLY | MSI_FLAG_DEV_SYSFS;
if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE))
info->flags |= MSI_FLAG_MUST_REACTIVATE;

--- a/drivers/pci/msi/legacy.c
+++ b/drivers/pci/msi/legacy.c
@@ -77,5 +77,4 @@ void pci_msi_legacy_teardown_msi_irqs(st
{
msi_device_destroy_sysfs(&dev->dev);
arch_teardown_msi_irqs(dev);
- msi_free_msi_descs(&dev->dev);
}
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