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

[Alex Chiang]

* Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>:
> Fix kernel oops in pci_release_slot() when dbg() is enabled.

Merged, thanks.

/ac

> 
> 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@xxxxxxxxxxxxxx>
> 
> ---
>  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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