Plug a memory leak

Addressing:
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:208:
alloc_fn: Storage is returned from allocation function "strdup".
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:208:
var_assign: Assigning: "s" = storage returned from
"strdup(oval_ipv4_string)".
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:209:
identity_transfer: Passing "s" as argument 1 to function "strchr", which
returns an offset off that argument.
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:209:
noescape: Resource "s" is not freed or pointed-to in "strchr".
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:209:
var_assign: Assigning: "pfx" = storage returned from "strchr(s, 47)".
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:215:
noescape: Resource "pfx" is not freed or pointed-to in "sscanf".
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:222:
leaked_storage: Variable "pfx" going out of scope leaks the storage it
points to.
openscap-1.3.0_alpha3/src/OVAL/results/oval_cmp_ip_address.c:222:
leaked_storage: Variable "s" going out of scope leaks the storage it
points to.

Author: jan-cerny

src/OVAL/results/oval_cmp_ip_address.c

@@ -219,6 +219,7 @@ static inline int ipv4addr_parse(const char *oval_ipv4_string, uint32_t *netmask
 			*netmask_out = (~0u) << (32u - nm[0]);
 		} else {
 			dW("Invalid prefix or netmask.");
+			free(s);
 			return -1;
 		}
 	} else {