| Date | Fri, 30 Jul 2010 10:52:18 -0700 | From | Greg KH <> | Subject | [121/205] x86, pci, mrst: Add extra sanity check in walking the PCI extended cap chain |
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2.6.34-stable review patch. If anyone has any objections, please let us know.
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From: Jacob Pan <jacob.jun.pan@linux.intel.com>
commit f82c3d71d6fd2e6a3e3416f09099e29087e39abf upstream.
The fixed bar capability structure is searched in PCI extended configuration space. We need to make sure there is a valid capability ID to begin with otherwise, the search code may stuck in a infinite loop which results in boot hang. This patch adds additional check for cap ID 0, which is also invalid, and indicates end of chain.
End of chain is supposed to have all fields zero, but that doesn't seem to always be the case in the field.
Suggested-by: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> LKML-Reference: <1279306706-27087-1-git-send-email-jacob.jun.pan@linux.intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/pci/mrst.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/arch/x86/pci/mrst.c +++ b/arch/x86/pci/mrst.c @@ -66,8 +66,9 @@ static int fixed_bar_cap(struct pci_bus devfn, pos, 4, &pcie_cap)) return 0; - if (pcie_cap == 0xffffffff) - return 0; + if (PCI_EXT_CAP_ID(pcie_cap) == 0x0000 || + PCI_EXT_CAP_ID(pcie_cap) == 0xffff) + break; if (PCI_EXT_CAP_ID(pcie_cap) == PCI_EXT_CAP_ID_VNDR) { raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number, @@ -76,7 +77,7 @@ static int fixed_bar_cap(struct pci_bus return pos; } - pos = pcie_cap >> 20; + pos = PCI_EXT_CAP_NEXT(pcie_cap); } return 0;
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