PCI/MSI: Destroy sysfs before freeing entries

PCI/MSI: Destroy sysfs before freeing entries

[Thomas Gleixner]

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@linutronix.de>
Cc: stable@vger.kernel.org
---
 drivers/pci/msi.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -370,6 +370,11 @@ 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) {
@@ -381,11 +386,6 @@ 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)

Re: PCI/MSI: Destroy sysfs before freeing entries

[Greg Kroah Hartmann]

On Tue, Nov 09, 2021 at 02:53:57PM +0100, Thomas Gleixner wrote:
> 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@linutronix.de>
> Cc: stable@vger.kernel.org
> ---
>  drivers/pci/msi.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>