[libvirt] [PATCH] util: Prevent libvirtd crash from virPCIDeviceAddressIsEqual()

[Alex Jia]

GDB backtrace:

Breakpoint 1, virPCIGetVirtualFunctionIndex (pf_sysfs_device_link=0x7fc04400f470 "/sys/bus/pci/devices/0000:03:00.1", vf_sysfs_device_link=<optimized out>, vf_index=vf_index at entry=0x7fc06897b8f4)
    at util/virpci.c:2107
2107            if (virPCIDeviceAddressIsEqual(vf_bdf, virt_fns[i])) {
(gdb) p *vf_bdf
$1 = {domain = 0, bus = 3, slot = 16, function = 1}
(gdb) l
2102                             "virtual_functions"), pf_sysfs_device_link);
2103            goto out;
2104        }
2105
2106        for (i = 0; i < num_virt_fns; i++) {
2107            if (virPCIDeviceAddressIsEqual(vf_bdf, virt_fns[i])) {
2108                *vf_index = i;
2109                ret = 0;
2110                break;
2111            }
(gdb) p num_virt_fns
$46 = 2
(gdb) p virt_fns[0]
$48 = (virPCIDeviceAddressPtr) 0x0
(gdb) s
virPCIDeviceAddressIsEqual (bdf2=0x0, bdf1=0x7fc04400f330) at util/virpci.c:1844
1844                (bdf1->slot == bdf2->slot) &&
(gdb) s

Program received signal SIGSEGV, Segmentation fault.

RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=957416

Signed-off-by: Alex Jia <ajia at redhat.com>
---
 src/util/virpci.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/util/virpci.c b/src/util/virpci.c
index 97bba74..dda044c 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -1897,7 +1897,8 @@ static bool
 virPCIDeviceAddressIsEqual(virPCIDeviceAddressPtr bdf1,
                            virPCIDeviceAddressPtr bdf2)
 {
-    return ((bdf1->domain == bdf2->domain) &&
+    return (bdf1 && bdf2 &&
+            (bdf1->domain == bdf2->domain) &&
             (bdf1->bus == bdf2->bus) &&
             (bdf1->slot == bdf2->slot) &&
             (bdf1->function == bdf2->function));
-- 
1.7.1