linux-kernel - [PATCH 5.15 856/917] PCI/MSI: Destroy sysfs before freeing entries

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Date:   Mon, 15 Nov 2021 18:05:51 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Bjorn Helgaas <helgaas@...nel.org>
Subject: [PATCH 5.15 856/917] PCI/MSI: Destroy sysfs before freeing entries

From: Thomas Gleixner <tglx@...utronix.de>

commit 3735459037114d31e5acd9894fad9aed104231a0 upstream.

free_msi_irqs() frees the MSI entries before destroying the sysfs entries
which are exposing them. Nothing prevents a concurrent free while a sysfs
file is read and accesses the possibly freed entry.

Move the sysfs release ahead of freeing the entries.

Fixes: 1c51b50c2995 ("PCI/MSI: Export MSI mode using attributes, not kobjects")
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Bjorn Helgaas <helgaas@...nel.org>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/87sfw5305m.ffs@tglx
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/pci/msi.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -368,6 +368,11 @@ static void free_msi_irqs(struct pci_dev
 			for (i = 0; i < entry->nvec_used; i++)
 				BUG_ON(irq_has_action(entry->irq + i));
 
+	if (dev->msi_irq_groups) {
+		msi_destroy_sysfs(&dev->dev, dev->msi_irq_groups);
+		dev->msi_irq_groups = NULL;
+	}
+
 	pci_msi_teardown_msi_irqs(dev);
 
 	list_for_each_entry_safe(entry, tmp, msi_list, list) {
@@ -379,11 +384,6 @@ static void free_msi_irqs(struct pci_dev
 		list_del(&entry->list);
 		free_msi_entry(entry);
 	}
-
-	if (dev->msi_irq_groups) {
-		msi_destroy_sysfs(&dev->dev, dev->msi_irq_groups);
-		dev->msi_irq_groups = NULL;
-	}
 }
 
 static void pci_intx_for_msi(struct pci_dev *dev, int enable)