[libvirt] [PATCH v2] virnetdevtap: Don't crash on !ifname in virNetDevTapInterfaceStats

[Michal Privoznik]

https://bugzilla.redhat.com/show_bug.cgi?id=1595184

Some domain <interfaces/> do not have a name (because they are
not TAP devices). Therefore, if
virNetDevTapInterfaceStats(net->ifname, ...) is called an instant
crash occurs. In Linux version of the function strlen() is called
over the name and in BSD version STREQ() is called.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---

diff to v1:
- changed the error message
- fixed check in BSD version

 src/util/virnetdevtap.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/util/virnetdevtap.c b/src/util/virnetdevtap.c
index bd0710ad2e..3118ca18e8 100644
--- a/src/util/virnetdevtap.c
+++ b/src/util/virnetdevtap.c
@@ -691,6 +691,12 @@ virNetDevTapInterfaceStats(const char *ifname,
     FILE *fp;
     char line[256], *colon;
 
+    if (!ifname) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Interface name not provided"));
+        return -1;
+    }
+
     fp = fopen("/proc/net/dev", "r");
     if (!fp) {
         virReportSystemError(errno, "%s",
@@ -768,6 +774,12 @@ virNetDevTapInterfaceStats(const char *ifname,
     struct if_data *ifd;
     int ret = -1;
 
+    if (!ifname) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("Interface name not provided"));
+        return -1;
+    }
+
     if (getifaddrs(&ifap) < 0) {
         virReportSystemError(errno, "%s",
                              _("Could not get interface list"));
-- 
2.16.4