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[PATCH 8/16][BUG] PCI slot: Fix invalid memory access (Not for mainline!)

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To: Alex Chiang <achiang@...>, Greg KH <gregkh@...>
Cc: Gary Hade <garyhade@...>, Kristen Carlson Accardi <kristen.c.accardi@...>, Matthew Wilcox <matthew@...>, <warthog19@...>, <rick.jones2@...>, <linux-kernel@...>, <linux-pci@...>, <linux-acpi@...>
Date: Friday, March 21, 2008 - 12:15 am

Fix kernel oops in pci_release_slot() when dbg() is enabled.

The dbg() in pci_release_slot() cause a kernel oops (invalid memory
access) because it accesses slot after it is released. We need to
access slot before calling kobject_put().

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

---
 drivers/pci/slot.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Index: linux-2.6.25-rc6/drivers/pci/slot.c
===================================================================
--- linux-2.6.25-rc6.orig/drivers/pci/slot.c
+++ linux-2.6.25-rc6/drivers/pci/slot.c
@@ -191,13 +191,14 @@ EXPORT_SYMBOL_GPL(pci_create_slot);
 
 int pci_destroy_slot(struct pci_slot *slot)
 {
+	dbg("%s: decreased refcount to %d on %x:%d\n", __func__,
+	    atomic_read(&slot->kobj.kref.refcount) - 1, slot->bus->number,
+	    slot->number);
+
 	down_write(&pci_bus_sem);
 	kobject_put(&slot->kobj);
 	up_write(&pci_bus_sem);
 
-	dbg("%s: decreased refcount to %d on %x:%d\n", __func__,
-	    atomic_read(&slot->kobj.kref.refcount), slot->bus->number,
-	    slot->number);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_destroy_slot);


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Messages in current thread:
[PATCH 0/3, v10] PCI, ACPI: Physical PCI slot objects, Alex Chiang, (Tue Mar 18, 5:05 pm)
Re: [PATCH 0/3, v10] PCI, ACPI: Physical PCI slot objects, Kenji Kaneshige, (Fri Mar 21, 12:07 am)
[PATCH 8/16][BUG] PCI slot: Fix invalid memory access (Not ..., Kenji Kaneshige, (Fri Mar 21, 12:15 am)
[PATCH 1/3] Construct one fakephp slot per pci slot, Alex Chiang, (Tue Mar 18, 5:08 pm)
[PATCH 2/3] Introduce pci_slot, Alex Chiang, (Tue Mar 18, 5:09 pm)
Re: [PATCH 0/3, v10] PCI, ACPI: Physical PCI slot objects, Matthew Wilcox, (Tue Mar 18, 8:55 pm)
Re: [PATCH 0/3, v10] PCI, ACPI: Physical PCI slot objects, Kenji Kaneshige, (Tue Mar 18, 10:24 pm)
Re: [PATCH 0/3, v10] PCI, ACPI: Physical PCI slot objects, Kenji Kaneshige, (Tue Mar 18, 10:34 pm)
[PATCH 3/3] ACPI PCI slot detection driver, Alex Chiang, (Tue Mar 18, 5:09 pm)
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