linux-kernel - Re: [PATCH] PCI: acpiphp_ibm: fix null dereferences on null ibm

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Date:	Fri, 8 Jan 2016 12:14:42 -0600
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Colin King <colin.king@...onical.com>
Cc:	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <len.brown@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: acpiphp_ibm: fix null dereferences on null ibm_slot

On Sat, Jan 02, 2016 at 12:27:01AM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> ibm_slot_from_id can return null if the des header signature is
> not aPCI or if the kmalloc for the return acpi descriptore fails,
> causing potential null pointer dereferences on the return null
> descriptor.
> 
> Handle the null case with appropriate check and error return.
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>

Applied to pci/hotplug for v4.5, thanks, Colin!

> ---
>  drivers/pci/hotplug/acpiphp_ibm.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_ibm.c b/drivers/pci/hotplug/acpiphp_ibm.c
> index 6ca2399..9d16c9d 100644
> --- a/drivers/pci/hotplug/acpiphp_ibm.c
> +++ b/drivers/pci/hotplug/acpiphp_ibm.c
> @@ -154,7 +154,8 @@ static union apci_descriptor *ibm_slot_from_id(int id)
>  ibm_slot_done:
>  	if (ret) {
>  		ret = kmalloc(sizeof(union apci_descriptor), GFP_KERNEL);
> -		memcpy(ret, des, sizeof(union apci_descriptor));
> +		if (ret)
> +			memcpy(ret, des, sizeof(union apci_descriptor));
>  	}
>  	kfree(table);
>  	return ret;
> @@ -175,8 +176,13 @@ static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status)
>  	acpi_status stat;
>  	unsigned long long rc;
>  	union apci_descriptor *ibm_slot;
> +	int id = hpslot_to_sun(slot);
>  
> -	ibm_slot = ibm_slot_from_id(hpslot_to_sun(slot));
> +	ibm_slot = ibm_slot_from_id(id);
> +	if (!ibm_slot) {
> +		pr_err("APLS null ACPI descriptor for slot %d\n", id);
> +		return -ENODEV;
> +	}
>  
>  	pr_debug("%s: set slot %d (%d) attention status to %d\n", __func__,
>  			ibm_slot->slot.slot_num, ibm_slot->slot.slot_id,
> @@ -215,8 +221,13 @@ static int ibm_set_attention_status(struct hotplug_slot *slot, u8 status)
>  static int ibm_get_attention_status(struct hotplug_slot *slot, u8 *status)
>  {
>  	union apci_descriptor *ibm_slot;
> +	int id = hpslot_to_sun(slot);
>  
> -	ibm_slot = ibm_slot_from_id(hpslot_to_sun(slot));
> +	ibm_slot = ibm_slot_from_id(id);
> +	if (!ibm_slot) {
> +		pr_err("APLS null ACPI descriptor for slot %d\n", id);
> +		return -ENODEV;
> +	}
>  
>  	if (ibm_slot->slot.attn & 0xa0 || ibm_slot->slot.status[1] & 0x08)
>  		*status = 1;
> -- 
> 2.6.4
> 
> --
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