From f82c3d71d6fd2e6a3e3416f09099e29087e39abf Mon Sep 17 00:00:00 2001 From: Jacob Pan Date: Fri, 16 Jul 2010 11:58:26 -0700 Subject: [PATCH] x86, pci, mrst: Add extra sanity check in walking the PCI extended cap chain 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" Signed-off-by: Jacob Pan Reviewed-by: Jesse Barnes LKML-Reference: <1279306706-27087-1-git-send-email-jacob.jun.pan@linux.intel.com> Signed-off-by: H. Peter Anvin --- arch/x86/pci/mrst.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c index 7ef3a2735df3..cb29191cee58 100644 --- a/arch/x86/pci/mrst.c +++ b/arch/x86/pci/mrst.c @@ -66,8 +66,9 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn) 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 *bus, unsigned int devfn) return pos; } - pos = pcie_cap >> 20; + pos = PCI_EXT_CAP_NEXT(pcie_cap); } return 0; -- 2.20.1