zebra: Keep the interface flags safe on multiple ioctl calls

Trying to call multiple ioctl calls on ifreq will result in
overwriting ifreq with garbage data. On if_get_flags call,
try to keep the flags field safe from another possible ioctl
call before applying the flags field.

Modified code as per Code Review, done by Donald Sharp.

Signed-off-by: Bijan <bijanebrahimi@riseup.net>
(cherry picked from commit 16dca7cec5f47b7a6f83822a1e681652b7d2d60d)

diff --git a/zebra/ioctl.c b/zebra/ioctl.c
index 8b30eea9f1191647d15719980fd6af8b02aa7f0d..9b6aaf1d85ae73606a5e1ca956e8c37d5b9c909c 100644 (file)
--- a/zebra/ioctl.c
+++ b/zebra/ioctl.c
@@ -410,11 +410,14 @@ int if_unset_prefix_ctx(const struct zebra_dplane_ctx *ctx)
 void if_get_flags(struct interface *ifp)
 {
        int ret;
-       struct ifreq ifreq;
+       struct ifreq ifreqflags;
+       struct ifreq ifreqdata;
 
-       ifreq_set_name(&ifreq, ifp);
+       ifreq_set_name(&ifreqflags, ifp);
+       ifreq_set_name(&ifreqdata, ifp);
 
-       ret = vrf_if_ioctl(SIOCGIFFLAGS, (caddr_t)&ifreq, ifp->vrf->vrf_id);
+       ret = vrf_if_ioctl(SIOCGIFFLAGS, (caddr_t)&ifreqflags,
+                          ifp->vrf->vrf_id);
        if (ret < 0) {
                flog_err_sys(EC_LIB_SYSTEM_CALL,
                             "vrf_if_ioctl(SIOCGIFFLAGS %s) failed: %s",
@@ -448,8 +451,8 @@ void if_get_flags(struct interface *ifp)
        struct if_data ifd = {.ifi_link_state = 0};
        struct if_data *ifdata = &ifd;
 
-       ifreq.ifr_data = (caddr_t)ifdata;
-       ret = vrf_if_ioctl(SIOCGIFDATA, (caddr_t)&ifreq, ifp->vrf->vrf_id);
+       ifreqdata.ifr_data = (caddr_t)ifdata;
+       ret = vrf_if_ioctl(SIOCGIFDATA, (caddr_t)&ifreqdata, ifp->vrf->vrf_id);
 #endif
 
        if (ret == -1)
@@ -459,12 +462,12 @@ void if_get_flags(struct interface *ifp)
                             safe_strerror(errno));
        else {
                if (ifdata->ifi_link_state >= LINK_STATE_UP)
-                       SET_FLAG(ifreq.ifr_flags, IFF_RUNNING);
+                       SET_FLAG(ifreqflags.ifr_flags, IFF_RUNNING);
                else if (ifdata->ifi_link_state == LINK_STATE_UNKNOWN)
                        /* BSD traditionally treats UNKNOWN as UP */
-                       SET_FLAG(ifreq.ifr_flags, IFF_RUNNING);
+                       SET_FLAG(ifreqflags.ifr_flags, IFF_RUNNING);
                else
-                       UNSET_FLAG(ifreq.ifr_flags, IFF_RUNNING);
+                       UNSET_FLAG(ifreqflags.ifr_flags, IFF_RUNNING);
        }
 
 #elif defined(HAVE_BSD_LINK_DETECT)
@@ -489,14 +492,14 @@ void if_get_flags(struct interface *ifp)
                                     ifp->name, safe_strerror(errno));
        } else if (ifmr.ifm_status & IFM_AVALID) { /* media state is valid */
                if (ifmr.ifm_status & IFM_ACTIVE)  /* media is active */
-                       SET_FLAG(ifreq.ifr_flags, IFF_RUNNING);
+                       SET_FLAG(ifreqflags.ifr_flags, IFF_RUNNING);
                else
-                       UNSET_FLAG(ifreq.ifr_flags, IFF_RUNNING);
+                       UNSET_FLAG(ifreqflags.ifr_flags, IFF_RUNNING);
        }
 #endif /* HAVE_BSD_LINK_DETECT */
 
 out:
-       if_flags_update(ifp, (ifreq.ifr_flags & 0x0000ffff));
+       if_flags_update(ifp, (ifreqflags.ifr_flags & 0x0000ffff));
 }
 
 /* Set interface flags */