linux-kernel - [PATCH 3.16 027/305] PCI: Supply CPU physical address (not bus address) to iomem_is

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Message-ID: <lsq.1471110171.871305768@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Arjan van de Ven" <arjan@...ux.intel.com>,
	"Yinghai Lu" <yinghai@...nel.org>,
	"Bjorn Helgaas" <bhelgaas@...gle.com>
Subject: [PATCH 3.16 027/305] PCI: Supply CPU physical address (not bus
 address) to iomem_is_exclusive()

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Bjorn Helgaas <bhelgaas@...gle.com>

commit ca620723d4ff9ea7ed484eab46264c3af871b9ae upstream.

iomem_is_exclusive() requires a CPU physical address, but on some arches we
supplied a PCI bus address instead.

On most arches, pci_resource_to_user(res) returns "res->start", which is a
CPU physical address.  But on microblaze, mips, powerpc, and sparc, it
returns the PCI bus address corresponding to "res->start".

The result is that pci_mmap_resource() may fail when it shouldn't (if the
bus address happens to match an existing resource), or it may succeed when
it should fail (if the resource is exclusive but the bus address doesn't
match it).

Call iomem_is_exclusive() with "res->start", which is always a CPU physical
address, not the result of pci_resource_to_user().

Fixes: e8de1481fd71 ("resource: allow MMIO exclusivity for device drivers")
Suggested-by: Yinghai Lu <yinghai@...nel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
CC: Arjan van de Ven <arjan@...ux.intel.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/pci/pci-sysfs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1005,6 +1005,9 @@ static int pci_mmap_resource(struct kobj
 	if (i >= PCI_ROM_RESOURCE)
 		return -ENODEV;
 
+	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
+		return -EINVAL;
+
 	if (!pci_mmap_fits(pdev, i, vma, PCI_MMAP_SYSFS)) {
 		WARN(1, "process \"%s\" tried to map 0x%08lx bytes at page 0x%08lx on %s BAR %d (start 0x%16Lx, size 0x%16Lx)\n",
 			current->comm, vma->vm_end-vma->vm_start, vma->vm_pgoff,
@@ -1021,10 +1024,6 @@ static int pci_mmap_resource(struct kobj
 	pci_resource_to_user(pdev, i, res, &start, &end);
 	vma->vm_pgoff += start >> PAGE_SHIFT;
 	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
-
-	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(start))
-		return -EINVAL;
-
 	return pci_mmap_page_range(pdev, vma, mmap_type, write_combine);
 }