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Commit cf26e8dc authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

pcmcia: do not autoadd root PCI bus resources 



On the PCI root bus on the x86 architecture, the risk of hitting
some strange system devices is too high: If a driver isn't loaded,
the resources are not claimed; even if a driver is loaded, it
may not request all resources or even the wrong one. We can neither
trust the rest of the kernel nor ACPI/PNP and CRS parsing to get it
right.

Therefore, explicitly spell out what safeguards we provide, and add
a safeguard to only use resources which are set up exclusively for
the secondary PCI bus (non-subtractive mode): the risk of hitting
system devices is quite low, as they usually aren't connected to
the secondary PCI bus.

CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent b19a7275

drivers/pcmcia/rsrc_nonstatic.c

+29 −6
Original line number Diff line number Diff line
@@ -935,23 +935,42 @@ static int nonstatic_autoadd_resources(struct pcmcia_socket *s) 
		return -ENODEV;



#if defined(CONFIG_X86)

	/* If this is the root bus, the risk of hitting

	 * some strange system devices which aren't protected

	 * by either ACPI resource tables or properly requested

	 * resources is too big. Therefore, don't do auto-adding

	 * of resources at the moment.

	/* If this is the root bus, the risk of hitting some strange

	 * system devices is too high: If a driver isn't loaded, the

	 * resources are not claimed; even if a driver is loaded, it

	 * may not request all resources or even the wrong one. We

	 * can neither trust the rest of the kernel nor ACPI/PNP and

	 * CRS parsing to get it right. Therefore, use several

	 * safeguards:

	 *

	 * - Do not auto-add resources if the CardBus bridge is on

	 *   the PCI root bus

	 *

	 * - Avoid any I/O ports < 0x100.

	 *

	 * - On PCI-PCI bridges, only use resources which are set up

	 *   exclusively for the secondary PCI bus: the risk of hitting

	 *   system devices is quite low, as they usually aren't

	 *   connected to the secondary PCI bus.

	 */

	if (s->cb_dev->bus->number == 0)

		return -EINVAL;

#endif



	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++) {

		res = s->cb_dev->bus->resource[i];

#else

	pci_bus_for_each_resource(s->cb_dev->bus, res, i) {

#endif

		if (!res)

			continue;



		if (res->flags & IORESOURCE_IO) {

			/* safeguard against the root resource, where the

			 * risk of hitting any other device would be too

			 * high */

			if (res == &ioport_resource)

				continue;



			dev_printk(KERN_INFO, &s->cb_dev->dev,

				   "pcmcia: parent PCI bridge window: %pR\n",

				   res);
@@ -961,8 +980,12 @@ static int nonstatic_autoadd_resources(struct pcmcia_socket *s) 
		}



		if (res->flags & IORESOURCE_MEM) {

			/* safeguard against the root resource, where the

			 * risk of hitting any other device would be too

			 * high */

			if (res == &iomem_resource)

				continue;



			dev_printk(KERN_INFO, &s->cb_dev->dev,

				   "pcmcia: parent PCI bridge window: %pR\n",

				   res);