[gnome-applets/gnome-3-38: 3/3] netspeed: correct handling if no IPv4 address set

[Alberts Muktupāvels <muktupavels src gnome org>]

commit c0c7537039b1b2a4a3f5ba4798e8c4dd42ec0aec
Author: treysis <treysis gmx net>
Date:   Wed Jan 20 16:02:19 2021 +0100

    netspeed: correct handling if no IPv4 address set
    
    https://gitlab.gnome.org/GNOME/gnome-applets/-/issues/20

 gnome-applets/netspeed/backend.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/gnome-applets/netspeed/backend.c b/gnome-applets/netspeed/backend.c
index 6e336a251..8c9bc3789 100644
--- a/gnome-applets/netspeed/backend.c
+++ b/gnome-applets/netspeed/backend.c
@@ -140,7 +140,12 @@ free_device_info(DevInfo *devinfo)
 static char*
 format_ipv4(guint32 ip)
 {
-       char *str = g_malloc(INET_ADDRSTRLEN);
+       char *str;
+       
+       if (ip == 0)
+               return NULL;
+
+       str = g_malloc(INET_ADDRSTRLEN);
        inet_ntop(AF_INET, &ip, str, INET_ADDRSTRLEN);
        return str;
 }