[PATCH] util: fix very old bug/typo in virNetDevParseVfInfo()

Laine Stump laine at redhat.com
Wed Oct 21 02:38:25 UTC 2020

When this function was recently changed to add in parsing of
IFLA_VF_STATS, I noticed that the checks for existence of IFLA_VF_MAC
and IFLA_VF_VLAN were looking in the *wrong array*. The array that
contains the results of parsing each IFLA_VFINFO in
tb[IFLA_VFINFO_LIST] is tb_vf, but we were checking for these in tb
(which is the array containing the results of the toplevel parsing of
the netlink message, *not* the results of parsing one of the nested

This incorrect code has been here since the function was originally
written in 2012. It has only worked all these years due to coincidence
- the items at those indexes in tb are IFLA_ADDRESS and IFLA_BROADCAST
(of the *PF*, not of any of its VFs), and those happen to always be
present in the toplevel netlink message; since we are only looking in
the incorrect place to check for mere existence of the attribute (but
are doing the actual retrieval of the attribute from the correct
place), this bug has no real consequences other than confusing anyone
trying to understand the code.

Signed-off-by: Laine Stump <laine at redhat.com>
 src/util/virnetdev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index e284d62233..591a73cb45 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -1691,7 +1691,7 @@ virNetDevParseVfInfo(struct nlattr **tb, int32_t vf, virMacAddrPtr mac,
             return rc;
-        if (mac && tb[IFLA_VF_MAC]) {
+        if (mac && tb_vf[IFLA_VF_MAC]) {
             vf_mac = RTA_DATA(tb_vf[IFLA_VF_MAC]);
             if (vf_mac && vf_mac->vf == vf)  {
                 virMacAddrSetRaw(mac, vf_mac->mac);
@@ -1699,7 +1699,7 @@ virNetDevParseVfInfo(struct nlattr **tb, int32_t vf, virMacAddrPtr mac,
-        if (vlanid && tb[IFLA_VF_VLAN]) {
+        if (vlanid && tb_vf[IFLA_VF_VLAN]) {
             vf_vlan = RTA_DATA(tb_vf[IFLA_VF_VLAN]);
             if (vf_vlan && vf_vlan->vf == vf)  {
                 *vlanid = vf_vlan->vlan;

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