linux-kernel - [tip: irq/urgent] PCI/MSI: Prevent UAF in error path

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Date:   Fri, 21 Jan 2022 01:18:57 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Tong Zhang <ztong0001@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, maz@...nel.org
Subject: [tip: irq/urgent] PCI/MSI: Prevent UAF in error path

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     a0af3d1104f752b6d0dba71788e3fddd67c857a7
Gitweb:        https://git.kernel.org/tip/a0af3d1104f752b6d0dba71788e3fddd67c857a7
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Wed, 19 Jan 2022 18:54:52 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Fri, 21 Jan 2022 02:14:46 +01:00

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@...il.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Tong Zhang <ztong0001@...il.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Link: https://lore.kernel.org/r/87r1938vbn.ffs@tglx
---
 drivers/pci/msi/irqdomain.c | 4 ++--
 drivers/pci/msi/legacy.c    | 1 -
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 0d63541..e9cf318 100644
--- 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
--- 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);
 }