From 88742c058074294c633dbdcaee1e064fe84456f3 Mon Sep 17 00:00:00 2001
From: Sai Asish Y <say.apm35@gmail.com>
Date: Thu, 2 Jul 2026 03:14:52 -0700
Subject: [PATCH] Guard memcpy against NULL when storing an empty string value

Signed-off-by: Sai Asish Y <say.apm35@gmail.com>
---
 src/value.c       |  3 ++-
 tests/test-json.c | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/value.c b/src/value.c
index 550e2bc..9f3f98a 100644
--- a/src/value.c
+++ b/src/value.c
@@ -435,7 +435,8 @@ value_init_string_(VALUE* v, const char* str, size_t len)
     }
     payload[off++] = tmplen & 0x7f;
 
-    memcpy(payload + off, str, len);
+    if(len > 0)
+        memcpy(payload + off, str, len);
     payload[off + len] = '\0';
     return 0;
 }
diff --git a/tests/test-json.c b/tests/test-json.c
index e9f4f01..a236a8e 100644
--- a/tests/test-json.c
+++ b/tests/test-json.c
@@ -1519,6 +1519,26 @@ test_issue3(void)
     value_fini(&root);
 }
 
+static void
+test_issue13(void)
+{
+    static const char input[] = "{\"\":1}";
+
+    VALUE root;
+    VALUE* v;
+
+    /* An empty object key must parse without passing a NULL pointer to
+     * memcpy() while storing the zero-length key string. */
+    TEST_CHECK(json_dom_parse(input, strlen(input), NULL, 0, &root, NULL) == 0);
+    TEST_CHECK(value_dict_size(&root) == 1);
+
+    v = value_dict_get_(&root, "", 0);
+    if(TEST_CHECK(v != NULL))
+        TEST_CHECK(value_int32(v) == 1);
+
+    value_fini(&root);
+}
+
 
 TEST_LIST = {
     { "pos-tracking",               test_pos_tracking },
@@ -1548,5 +1568,6 @@ TEST_LIST = {
     { "crazy-double",               test_crazy_double },
     { "bug-issue2",                 test_issue2 },
     { "bug-issue3",                 test_issue3 },
+    { "bug-issue13",                test_issue13 },
     { 0 }
 };