link: fix memory leaks due to repeated calls to .io_alloc()

All the io_alloc() implementation unconditionally allocated
new memory, thus leaking memory if called more then once.
Fix io_alloc() implementations not to allocate new memory
if not needed.

This happens for example in link_msg_parser() which first
calls rtnl_link_set_type():

    #0  macvlan_alloc (link=0x609d50) at route/link/macvlan.c:56
    #1  0x00007ffff7b99a78 in rtnl_link_set_type (link=link@entry=0x609d50, type=type@entry=0x609a94 "macvlan") at route/link.c:2233
    #2  0x00007ffff7b99c28 in link_msg_parser (ops=<optimized out>, who=<optimized out>, n=<optimized out>, pp=0x7fffffffd870) at route/link.c:547
    #3  0x00007ffff7dea109 in nl_cache_parse (ops=0x7ffff7dd8600 <rtnl_link_ops>, who=0x603338, nlh=0x6098a0, params=0x7fffffffd870) at cache.c:914
    #4  0x00007ffff7dea15b in update_msg_parser (msg=<optimized out>, arg=<optimized out>) at cache.c:668
    #5  0x00007ffff7def7bf in nl_cb_call (msg=<optimized out>, type=<optimized out>, cb=<optimized out>) at ../include/netlink-private/netlink.h:142
    #6  recvmsgs (cb=0x6057a0, sk=0x6034c0) at nl.c:952
    #7  nl_recvmsgs_report (sk=sk@entry=0x6034c0, cb=cb@entry=0x6057a0) at nl.c:1003
    #8  0x00007ffff7defb79 in nl_recvmsgs (sk=sk@entry=0x6034c0, cb=cb@entry=0x6057a0) at nl.c:1027
    #9  0x00007ffff7de9668 in __cache_pickup (sk=0x6034c0, cache=0x603510, param=param@entry=0x7fffffffd870) at cache.c:701
    #10 0x00007ffff7dea08d in nl_cache_pickup (sk=<optimized out>, cache=<optimized out>) at cache.c:753
    #11 0x0000000000400d56 in main ()

and later ops->io_parse():

    #0  macvlan_alloc (link=0x609d50) at route/link/macvlan.c:56
    #1  0x00007ffff7baae9d in macvlan_parse (link=0x609d50, data=<optimized out>, xstats=<optimized out>) at route/link/macvlan.c:79
    #2  0x00007ffff7b99c80 in link_msg_parser (ops=<optimized out>, who=<optimized out>, n=<optimized out>, pp=0x7fffffffd870) at route/link.c:567
    #3  0x00007ffff7dea109 in nl_cache_parse (ops=0x7ffff7dd8600 <rtnl_link_ops>, who=0x603338, nlh=0x6098a0, params=0x7fffffffd870) at cache.c:914
    #4  0x00007ffff7dea15b in update_msg_parser (msg=<optimized out>, arg=<optimized out>) at cache.c:668
    #5  0x00007ffff7def7bf in nl_cb_call (msg=<optimized out>, type=<optimized out>, cb=<optimized out>) at ../include/netlink-private/netlink.h:142
    #6  recvmsgs (cb=0x6057a0, sk=0x6034c0) at nl.c:952
    #7  nl_recvmsgs_report (sk=sk@entry=0x6034c0, cb=cb@entry=0x6057a0) at nl.c:1003
    #8  0x00007ffff7defb79 in nl_recvmsgs (sk=sk@entry=0x6034c0, cb=cb@entry=0x6057a0) at nl.c:1027
    #9  0x00007ffff7de9668 in __cache_pickup (sk=0x6034c0, cache=0x603510, param=param@entry=0x7fffffffd870) at cache.c:701
    #10 0x00007ffff7dea08d in nl_cache_pickup (sk=<optimized out>, cache=<optimized out>) at cache.c:753
    #11 0x0000000000400d56 in main ()

https://github.com/thom311/libnl/issues/59

Signed-off-by: Thomas Haller <thaller@redhat.com>

lib/route/link/can.c

@@ -73,11 +73,15 @@ static int can_alloc(struct rtnl_link *link)
 {
 	struct can_info *ci;
 
-	ci = calloc(1, sizeof(*ci));
-	if (!ci)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*ci));
+	else {
+		ci = calloc(1, sizeof(*ci));
+		if (!ci)
+			return -NLE_NOMEM;
 
-	link->l_info = ci;
+		link->l_info = ci;
+	}
 
 	return 0;
 }

lib/route/link/ip6tnl.c

@@ -73,11 +73,15 @@ static int ip6_tnl_alloc(struct rtnl_link *link)
 {
 	struct ip6_tnl_info *ip6_tnl;
 
-	ip6_tnl = calloc(1, sizeof(*ip6_tnl));
-	if (!ip6_tnl)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*ip6_tnl));
+	else {
+		ip6_tnl = calloc(1, sizeof(*ip6_tnl));
+		if (!ip6_tnl)
+			return -NLE_NOMEM;
 
-	link->l_info = ip6_tnl;
+		link->l_info = ip6_tnl;
+	}
 
 	return 0;
 }

lib/route/link/ipgre.c

@@ -75,11 +75,15 @@ static int ipgre_alloc(struct rtnl_link *link)
 {
 	struct ipgre_info *ipgre;
 
-	ipgre = calloc(1, sizeof(*ipgre));
-	if (!ipgre)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*ipgre));
+	else {
+		ipgre = calloc(1, sizeof(*ipgre));
+		if (!ipgre)
+			return -NLE_NOMEM;
 
-	link->l_info = ipgre;
+		link->l_info = ipgre;
+	}
 
 	return 0;
 }

lib/route/link/ipip.c

@@ -62,11 +62,15 @@ static int ipip_alloc(struct rtnl_link *link)
 {
 	struct ipip_info *ipip;
 
-	ipip = calloc(1, sizeof(*ipip));
-	if (!ipip)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*ipip));
+	else {
+		ipip = calloc(1, sizeof(*ipip));
+		if (!ipip)
+			return -NLE_NOMEM;
 
-	link->l_info = ipip;
+		link->l_info = ipip;
+	}
 
 	return 0;
 }

lib/route/link/ipvti.c

@@ -59,11 +59,15 @@ static int ipvti_alloc(struct rtnl_link *link)
 {
 	struct ipvti_info *ipvti;
 
-	ipvti = calloc(1, sizeof(*ipvti));
-	if (!ipvti)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*ipvti));
+	else {
+		ipvti = calloc(1, sizeof(*ipvti));
+		if (!ipvti)
+			return -NLE_NOMEM;
 
-	link->l_info = ipvti;
+		link->l_info = ipvti;
+	}
 
 	return 0;
 }

lib/route/link/macvlan.c

@@ -55,10 +55,14 @@ static int macvlan_alloc(struct rtnl_link *link)
 {
 	struct macvlan_info *mvi;
 
-	if ((mvi = calloc(1, sizeof(*mvi))) == NULL)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*mvi));
+	else {
+		if ((mvi = calloc(1, sizeof(*mvi))) == NULL)
+			return -NLE_NOMEM;
 
-	link->l_info = mvi;
+		link->l_info = mvi;
+	}
 
 	return 0;
 }

lib/route/link/sit.c

@@ -69,11 +69,15 @@ static int sit_alloc(struct rtnl_link *link)
 {
 	struct sit_info *sit;
 
-	sit = calloc(1, sizeof(*sit));
-	if (!sit)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*sit));
+	else {
+		sit = calloc(1, sizeof(*sit));
+		if (!sit)
+			return -NLE_NOMEM;
 
-	link->l_info = sit;
+		link->l_info = sit;
+	}
 
 	return 0;
 }

lib/route/link/vlan.c

@@ -67,10 +67,16 @@ static int vlan_alloc(struct rtnl_link *link)
 {
 	struct vlan_info *vi;
 
-	if ((vi = calloc(1, sizeof(*vi))) == NULL)
-		return -NLE_NOMEM;
+	if (link->l_info) {
+		vi = link->l_info;
+		free(vi->vi_egress_qos);
+		memset(link->l_info, 0, sizeof(*vi));
+	} else {
+		if ((vi = calloc(1, sizeof(*vi))) == NULL)
+			return -NLE_NOMEM;
 
-	link->l_info = vi;
+		link->l_info = vi;
+	}
 
 	return 0;
 }

lib/route/link/vxlan.c

@@ -91,10 +91,14 @@ static int vxlan_alloc(struct rtnl_link *link)
 {
 	struct vxlan_info *vxi;
 
-	if ((vxi = calloc(1, sizeof(*vxi))) == NULL)
-		return -NLE_NOMEM;
+	if (link->l_info)
+		memset(link->l_info, 0, sizeof(*vxi));
+	else {
+		if ((vxi = calloc(1, sizeof(*vxi))) == NULL)
+			return -NLE_NOMEM;
 
-	link->l_info = vxi;
+		link->l_info = vxi;
+	}
 
 	return 0;
 }