[PATCH] util: check ifa_addr pointer before accessing its elements

[Pavel Hrdina <phrdina@xxxxxxxxxx>]

Reported by Rafał Wojciechowski <it@xxxxxxxxxxxxxxxxxxxxx>.

Thread 1 (Thread 0x7f194b99d700 (LWP 5631)):
0  virNetDevGetifaddrsAddress (addr=0x7f194b99c7c0, ifname=0x7f193400e2b0 "ovirtmgmt") at util/virnetdevip.c:738
1  virNetDevIPAddrGet (ifname=0x7f193400e2b0 "ovirtmgmt", addr=addr@entry=0x7f194b99c7c0) at util/virnetdevip.c:795
2  0x00007f19467800d6 in networkGetNetworkAddress (netname=<optimized out>, netaddr=netaddr@entry=0x7f1924013f18) at network/bridge_driver.c:4780
3  0x00007f193e43a33c in qemuProcessGraphicsSetupNetworkAddress (listenAddr=0x7f19340f7650 "127.0.0.1", glisten=0x7f1924013f10) at qemu/qemu_process.c:4062
4  qemuProcessGraphicsSetupListen (vm=<optimized out>, graphics=0x7f1924014f10, cfg=0x7f1934119f00) at qemu/qemu_process.c:4133
5  qemuProcessSetupGraphics (flags=17, vm=0x7f19240155d0, driver=0x7f193411f1d0) at qemu/qemu_process.c:4196
6  qemuProcessPrepareDomain (conn=conn@entry=0x7f192c00ab50, driver=driver@entry=0x7f193411f1d0, vm=vm@entry=0x7f19240155d0, flags=flags@entry=17) at qemu/qemu_process.c:4969
7  0x00007f193e4417c0 in qemuProcessStart (conn=conn@entry=0x7f192c00ab50, driver=driver@entry=0x7f193411f1d0, vm=0x7f19240155d0,asyncJob=asyncJob@entry=QEMU_ASYNC_JOB_START, migrateFrom=migrateFrom@entry=0x0, migrateFd=migrateFd@entry=-1, migratePath=migratePath@entry=0x0,snapshot=snapshot@entry=0x0, vmop=vmop@entry=VIR_NETDEV_VPORT_PROFILE_OP_CREATE, flags=17, flags@entry=1) at qemu/qemu_process.c:5553

Man page for getifaddrs also states that the "ifa_addr" may contain
a null pointer which happens if there is an existing network interface
on the host without IP address.

Signed-off-by: Pavel Hrdina <phrdina@xxxxxxxxxx>
---
 src/util/virnetdevip.c  | 7 ++++++-
 src/util/virnetdevtap.c | 3 +++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/util/virnetdevip.c b/src/util/virnetdevip.c
index 726fa6c3e3..09925e1d74 100644
--- a/src/util/virnetdevip.c
+++ b/src/util/virnetdevip.c
@@ -902,10 +902,15 @@ virNetDevGetifaddrsAddress(const char *ifname,
     }
 
     for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
-        int family = ifa->ifa_addr->sa_family;
+        int family;
 
         if (STRNEQ_NULLABLE(ifa->ifa_name, ifname))
             continue;
+
+        if (!ifa->ifa_addr)
+            continue;
+        family = ifa->ifa_addr->sa_family;
+
         if (family != AF_INET6 && family != AF_INET)
             continue;
 
diff --git a/src/util/virnetdevtap.c b/src/util/virnetdevtap.c
index 02ef7fd240..93002b9294 100644
--- a/src/util/virnetdevtap.c
+++ b/src/util/virnetdevtap.c
@@ -762,6 +762,9 @@ virNetDevTapInterfaceStats(const char *ifname,
     }
 
     for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
+        if (!ifa->ifa_addr)
+            continue;
+
         if (ifa->ifa_addr->sa_family != AF_LINK)
             continue;
 
-- 
2.12.2

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