virDeviceHasPCIExpressLink() wasn't checking that pcie_cap_pos was valid before attempting to use it, which could lead to reading the byte at offset 0+PCI_CAP_ID_EXP instead of [valid offset]+PCI_CAP_ID_EXP. In particular, this could happen for "integrated" PCI devices (those that are on the PCIe root complex). If it happened that the byte from the wrong address had the "right" bit set, then it would lead to us innappropriately believing that Express Link info was available when it wasn't, and the node device driver would log an error like this: virPCIDeviceGetLinkCapSta:2754 : internal error: pci device 0000:00:18.0 is not a PCI-Express device during a libvirtd restart. (this didn't ever occur until after virPCIDeviceIsPCIExpress() was made more intelligent in commit c00b6b1ae, which hasn't yet been in any official release) Signed-off-by: Laine Stump <laine(a)redhat.com&gt; --- src/util/virpci.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/util/virpci.c b/src/util/virpci.c index 9bfc743fbd..50fd5ef7ea 100644 --- a/src/util/virpci.c +++ b/src/util/virpci.c @@ -2722,6 +2722,11 @@ virPCIDeviceHasPCIExpressLink(virPCIDevicePtr dev) if (virPCIDeviceInit(dev, fd) < 0) goto cleanup; + if (dev->pcie_cap_pos == 0) { + ret = 0; + goto cleanup; + } + cap = virPCIDeviceRead16(dev, fd, dev->pcie_cap_pos + PCI_CAP_FLAGS); type = (cap & PCI_EXP_FLAGS_TYPE) >> 4; -- 2.29.2