linux-kernel - Re: [RFC PATCH 02/12] On Tue, 23 Sep 2008, David Miller wrote:

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Message-Id: <200810021523.45884.jbarnes@virtuousgeek.org>
Date:	Thu, 2 Oct 2008 15:23:43 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:	linux-kernel@...r.kernel.org, linux-netdev@...r.kernel.org,
	kkeil@...e.de, agospoda@...hat.com, arjan@...ux.intel.com,
	david.graham@...el.com, bruce.w.allan@...el.com, jkosina@...e.cz,
	john.ronciak@...el.com, tglx@...utronix.de,
	chris.jones@...onical.com, tim.gardner@...el.com, airlied@...il.com
Subject: Re: [RFC PATCH 02/12] On Tue, 23 Sep 2008, David Miller wrote:

Ping DaveM.  Does this look ok?  What else would we need for you to remove 
your range checking from sparc?

Thanks,
Jesse

On Monday, September 29, 2008 8:19 pm Jesse Brandeburg wrote:
> From: Jesse Barnes <jbarnes@...tuousgeek.org>
>
> > I did some snooping around, and while doing so I noticed that the PCI
> > mmap code for x86 doesn't do one bit of range checking on the size, or
> > any other aspect of the request, wrt. the MMIO regions actually mapped
> > in the BARs of the PCI device.
>
> Here's a patch that adds range checking to the sysfs mappings at
> least.  This patch should catch the case where X (or some other
> process) tries to map beyond the specific BAR it's (supposedly)
> trying to access, making things safer in general.  FWIW both my
> F9 and development versions of X start up fine with this patch
> applied.
>
> DaveM, will this work for you on sparc?  It looked like your code
> was allowing bridge window mappings, but that behavior should be
> preserved as long as your bridge devices reflect their window
> sizes correctly in their pdev->resources?
>
> If we add similar code to the procfs stuff we wouldn't need to do
> any checking in the arches.
>
> Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
> ---
>
>  drivers/pci/pci-sysfs.c |   14 ++++++++++++++
>  1 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 9c71858..4d1aa6e 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -16,6 +16,7 @@
>
>
>  #include <linux/kernel.h>
> +#include <linux/sched.h>
>  #include <linux/pci.h>
>  #include <linux/stat.h>
>  #include <linux/topology.h>
> @@ -502,6 +503,8 @@ pci_mmap_resource(struct kobject *kobj, struct
> bin_attribute *attr, struct resource *res = (struct resource
> *)attr->private;
>  	enum pci_mmap_state mmap_type;
>  	resource_size_t start, end;
> +	unsigned long map_len = vma->vm_end - vma->vm_start;
> +	unsigned long map_offset = vma->vm_pgoff << PAGE_SHIFT;
>  	int i;
>
>  	for (i = 0; i < PCI_ROM_RESOURCE; i++)
> @@ -510,6 +513,17 @@ pci_mmap_resource(struct kobject *kobj, struct
> bin_attribute *attr, if (i >= PCI_ROM_RESOURCE)
>  		return -ENODEV;
>
> +	/*
> +	 * Make sure the range the user is trying to map falls within
> +	 * the resource
> +	 */
> +	if (map_offset + map_len > pci_resource_len(pdev, i)) {
> +		WARN(1, "process \"%s\" tried to map 0x%08lx-0x%08lx on BAR %d (size
> 0x%08lx)\n", +		     current->comm, map_offset, map_offset + map_len, i,
> +		     (unsigned long)pci_resource_len(pdev, i));
> +		return -EINVAL;
> +	}
> +
>  	/* pci_mmap_page_range() expects the same kind of entry as coming
>  	 * from /proc/bus/pci/ which is a "user visible" value. If this is
>  	 * different from the resource itself, arch will do necessary fixup.
>
> --
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-- 
Jesse Barnes, Intel Open Source Technology Center
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