lib, ovs-vsctl: Add zero-initializations.

This commit adds zero-initializations by changing `SFL_ALLOC` from
`malloc` to `xzalloc`, adding a `memset` call to `sflAlloc`,
initializing a `pollfd` struct variable with zeroes, and changing some
calls to `xmalloc` to `xzalloc`. This is to prevent potential data leaks
or undefined behavior from potentially uninitialized variables.

Some variables would always be initialized by either the code flow or
the compiler. Thus, some of the associated Coverity reports might be
false positives. That said, it is still considered best practice to
zero-initialize variables upfront just in case to ensure the overall
resilience and security of OVS, as long as they do not impact
performance-critical code. As a bonus, it would also make static
analyzer tools, such as Coverity, happy.

Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

lib/latch-unix.c

@@ -71,7 +71,7 @@ latch_set(struct latch *latch)
 bool
 latch_is_set(const struct latch *latch)
 {
-    struct pollfd pfd;
+    struct pollfd pfd = {0};
     int retval;
 
     pfd.fd = latch->fds[0];

lib/sflow_agent.c

@@ -510,8 +510,16 @@ void sfl_agent_sysError(SFLAgent *agent, char *modName, char *msg)
 
 static void * sflAlloc(SFLAgent *agent, size_t bytes)
 {
-    if(agent->allocFn) return (*agent->allocFn)(agent->magic, agent, bytes);
-    else return SFL_ALLOC(bytes);
+    void *alloc;
+
+    if (agent->allocFn) {
+        alloc = (*agent->allocFn)(agent->magic, agent, bytes);
+        ovs_assert(alloc);
+        memset(alloc, 0, bytes);
+    } else {
+        alloc = SFL_ALLOC(bytes);
+    }
+    return alloc;
 }
 
 static void sflFree(SFLAgent *agent, void *obj)

lib/sflow_api.h

@@ -337,7 +337,7 @@ void sfl_agent_sysError(SFLAgent *agent, char *modName, char *msg);
 
 u_int32_t sfl_receiver_samplePacketsSent(SFLReceiver *receiver);
 
-#define SFL_ALLOC malloc
+#define SFL_ALLOC xzalloc
 #define SFL_FREE free
 
 #endif /* SFLOW_API_H */

utilities/ovs-vsctl.c

@@ -575,15 +575,18 @@ add_bridge_to_cache(struct vsctl_context *vsctl_ctx,
                     struct ovsrec_bridge *br_cfg, const char *name,
                     struct vsctl_bridge *parent, int vlan)
 {
-    struct vsctl_bridge *br = xmalloc(sizeof *br);
+    struct vsctl_bridge *br = xzalloc(sizeof *br);
+
     br->br_cfg = br_cfg;
     br->name = xstrdup(name);
     ovs_list_init(&br->ports);
     br->parent = parent;
     br->vlan = vlan;
     hmap_init(&br->children);
+
     if (parent) {
         struct vsctl_bridge *conflict = find_vlan_bridge(parent, vlan);
+
         if (conflict) {
             VLOG_WARN("%s: bridge has multiple VLAN bridges (%s and %s) "
                       "for VLAN %d, but only one is allowed",
@@ -659,7 +662,7 @@ static struct vsctl_port *
 add_port_to_cache(struct vsctl_context *vsctl_ctx, struct vsctl_bridge *parent,
                   struct ovsrec_port *port_cfg)
 {
-    struct vsctl_port *port;
+    struct vsctl_port *port = xzalloc(sizeof *port);
 
     if (port_cfg->tag
         && *port_cfg->tag >= 0 && *port_cfg->tag <= 4095) {
@@ -671,7 +674,6 @@ add_port_to_cache(struct vsctl_context *vsctl_ctx, struct vsctl_bridge *parent,
         }
     }
 
-    port = xmalloc(sizeof *port);
     ovs_list_push_back(&parent->ports, &port->ports_node);
     ovs_list_init(&port->ifaces);
     port->port_cfg = port_cfg;