PCI/MSI: Prevent UAF in error path

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>
Tested-by: Tong Zhang <ztong0001@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/87r1938vbn.ffs@tglx

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 0d63541..e9cf318 100644 (file)
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -28,6 +28,7 @@ void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
                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_domain(struct fwnode_handle *fwnode,
        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;
 

diff --git a/drivers/pci/msi/legacy.c b/drivers/pci/msi/legacy.c
index cdbb468..db761ad 100644 (file)
--- a/drivers/pci/msi/legacy.c
+++ b/drivers/pci/msi/legacy.c
@@ -77,5 +77,4 @@ void pci_msi_legacy_teardown_msi_irqs(struct pci_dev *dev)
 {
        msi_device_destroy_sysfs(&dev->dev);
        arch_teardown_msi_irqs(dev);
-       msi_free_msi_descs(&dev->dev);
 }