Conflict:NA
Reference:https://downloads.isc.org/isc/dhcp/4.4.3-P1/patches/CVE-2022-2928.4-4-3.diff
---
 common/options.c               |  7 +++++
 common/tests/option_unittest.c | 54 ++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/common/options.c b/common/options.c
index 4e26094..8e5dfb1 100644
--- a/common/options.c
+++ b/common/options.c
@@ -4499,6 +4499,8 @@ add_option(struct option_state *options,
 	if (!option_cache_allocate(&oc, MDL)) {
 		log_error("No memory for option cache adding %s (option %d).",
 			  option->name, option_num);
+		/* Get rid of reference created during hash lookup. */
+		option_dereference(&option, MDL);
 		return 0;
 	}
 
@@ -4510,6 +4512,8 @@ add_option(struct option_state *options,
 			     MDL)) {
 		log_error("No memory for constant data adding %s (option %d).",
 			  option->name, option_num);
+		/* Get rid of reference created during hash lookup. */
+		option_dereference(&option, MDL);
 		option_cache_dereference(&oc, MDL);
 		return 0;
 	}
@@ -4518,6 +4522,9 @@ add_option(struct option_state *options,
 	save_option(&dhcp_universe, options, oc);
 	option_cache_dereference(&oc, MDL);
 
+	/* Get rid of reference created during hash lookup. */
+	option_dereference(&option, MDL);
+
 	return 1;
 }
 
diff --git a/common/tests/option_unittest.c b/common/tests/option_unittest.c
index 688762d..afd041c 100644
--- a/common/tests/option_unittest.c
+++ b/common/tests/option_unittest.c
@@ -283,6 +283,59 @@ ATF_TC_BODY(parse_code93_option, tc)
     }
 }
 
+ATF_TC(add_option_ref_cnt);
+
+ATF_TC_HEAD(add_option_ref_cnt, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+		"Verify add_option() does not leak option ref counts.");
+}
+
+ATF_TC_BODY(add_option_ref_cnt, tc)
+{
+	struct option_state *options = NULL;
+	struct option *option = NULL;
+	unsigned int cid_code = DHO_DHCP_CLIENT_IDENTIFIER;
+	char *cid_str = "1234";
+	int refcnt_before = 0;
+
+	// Look up the option we're going to add.
+	initialize_common_option_spaces();
+	if (!option_code_hash_lookup(&option, dhcp_universe.code_hash,
+				&cid_code, 0, MDL)) {
+		atf_tc_fail("cannot find option definition?");
+	}
+
+	// Get the option's reference count before we call add_options.
+	refcnt_before = option->refcnt;
+
+	// Allocate a option_state to which to add an option.
+	if (!option_state_allocate(&options, MDL)) {
+		atf_tc_fail("cannot allocat options state");
+	}
+
+	// Call add_option() to add the option to the option state.
+	if (!add_option(options, cid_code, cid_str, strlen(cid_str))) {
+		atf_tc_fail("add_option returned 0");
+	}
+
+	// Verify that calling add_option() only adds 1 to the option ref count.
+	if (option->refcnt != (refcnt_before + 1)) {
+		atf_tc_fail("after add_option(), count is wrong, before %d, after: %d",
+			    refcnt_before, option->refcnt);
+	}
+
+	// Derefrence the option_state, this should reduce the ref count to
+	// it's starting value.
+	option_state_dereference(&options, MDL);
+
+	// Verify that dereferencing option_state restores option ref count.
+	if (option->refcnt != refcnt_before) {
+		atf_tc_fail("after state deref, count is wrong, before %d, after: %d",
+			    refcnt_before, option->refcnt);
+	}
+}
+
 /* This macro defines main() method that will call specified
    test cases. tp and simple_test_case names can be whatever you want
    as long as it is a valid variable identifier. */
@@ -292,6 +345,7 @@ ATF_TP_ADD_TCS(tp)
     ATF_TP_ADD_TC(tp, pretty_print_option);
     ATF_TP_ADD_TC(tp, parse_X);
     ATF_TP_ADD_TC(tp, parse_code93_option);
+    ATF_TP_ADD_TC(tp, add_option_ref_cnt);
 
     return (atf_no_error());
 }
-- 
2.23.0