linux-kernel - [PATCH] PCI/ACPI: do not reference a pci device after it has been released

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Message-Id: <20220428142854.1065953-1-gregkh@linuxfoundation.org>
Date:   Thu, 28 Apr 2022 16:28:53 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     bhelgaas@...gle.com, rafael@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Len Brown <lenb@...nel.org>, linux-pci@...r.kernel.org,
        linux-acpi@...r.kernel.org, whitehat002 <hackyzh002@...il.com>
Subject: [PATCH] PCI/ACPI: do not reference a pci device after it has been released

In acpi_get_pci_dev(), the debugging message for when a PCI bridge is
not found uses a pointer to a pci device whose reference has just been
dropped.  The chance that this really is a device that is now been
removed from the system is almost impossible to happen, but to be safe,
let's print out the debugging message based on the acpi root device
which we do have a valid reference to at the moment.

Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Len Brown <lenb@...nel.org>
Cc: linux-pci@...r.kernel.org
Cc: linux-acpi@...r.kernel.org
Reported-by: whitehat002 <hackyzh002@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/acpi/pci_root.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 6f9e75d14808..ecda378dbc09 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -303,7 +303,8 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
 		 * case pdev->subordinate will be NULL for the parent.
 		 */
 		if (!pbus) {
-			dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
+			dev_dbg(&root->device->dev,
+				"dev %d, function %d is not a PCI-to-PCI bridge\n", dev, fn);
 			pdev = NULL;
 			break;
 		}
-- 
2.36.0