🚑 fix for #407

src/json.hpp

@@ -6981,6 +6981,7 @@ class basic_json
                 case 0xca: // float 32
                 {
                     // copy bytes in reverse order into the double variable
+                    check_length(v.size(), sizeof(float), 1);
                     float res;
                     for (size_t byte = 0; byte < sizeof(float); ++byte)
                     {
@@ -6993,6 +6994,7 @@ class basic_json
                 case 0xcb: // float 64
                 {
                     // copy bytes in reverse order into the double variable
+                    check_length(v.size(), sizeof(double), 1);
                     double res;
                     for (size_t byte = 0; byte < sizeof(double); ++byte)
                     {
@@ -7558,6 +7560,7 @@ class basic_json
 
             case 0xf9: // Half-Precision Float (two-byte IEEE 754)
             {
+                check_length(v.size(), 2, 1);
                 idx += 2; // skip two content bytes
 
                 // code from RFC 7049, Appendix D, Figure 3:
@@ -7589,6 +7592,7 @@ class basic_json
             case 0xfa: // Single-Precision Float (four-byte IEEE 754)
             {
                 // copy bytes in reverse order into the float variable
+                check_length(v.size(), sizeof(float), 1);
                 float res;
                 for (size_t byte = 0; byte < sizeof(float); ++byte)
                 {
@@ -7600,6 +7604,7 @@ class basic_json
 
             case 0xfb: // Double-Precision Float (eight-byte IEEE 754)
             {
+                check_length(v.size(), sizeof(double), 1);
                 // copy bytes in reverse order into the double variable
                 double res;
                 for (size_t byte = 0; byte < sizeof(double); ++byte)

src/json.hpp.re2c

@@ -6981,6 +6981,7 @@ class basic_json
                 case 0xca: // float 32
                 {
                     // copy bytes in reverse order into the double variable
+                    check_length(v.size(), sizeof(float), 1);
                     float res;
                     for (size_t byte = 0; byte < sizeof(float); ++byte)
                     {
@@ -6993,6 +6994,7 @@ class basic_json
                 case 0xcb: // float 64
                 {
                     // copy bytes in reverse order into the double variable
+                    check_length(v.size(), sizeof(double), 1);
                     double res;
                     for (size_t byte = 0; byte < sizeof(double); ++byte)
                     {
@@ -7558,6 +7560,7 @@ class basic_json
 
             case 0xf9: // Half-Precision Float (two-byte IEEE 754)
             {
+                check_length(v.size(), 2, 1);
                 idx += 2; // skip two content bytes
 
                 // code from RFC 7049, Appendix D, Figure 3:
@@ -7589,6 +7592,7 @@ class basic_json
             case 0xfa: // Single-Precision Float (four-byte IEEE 754)
             {
                 // copy bytes in reverse order into the float variable
+                check_length(v.size(), sizeof(float), 1);
                 float res;
                 for (size_t byte = 0; byte < sizeof(float); ++byte)
                 {
@@ -7600,6 +7604,7 @@ class basic_json
 
             case 0xfb: // Double-Precision Float (eight-byte IEEE 754)
             {
+                check_length(v.size(), sizeof(double), 1);
                 // copy bytes in reverse order into the double variable
                 double res;
                 for (size_t byte = 0; byte < sizeof(double); ++byte)

test/src/unit-regression.cpp

@@ -547,4 +547,27 @@ TEST_CASE("regression tests")
         std::vector<uint8_t> vec {0x65, 0xf5, 0x0a, 0x48, 0x21};
         CHECK_THROWS_AS(json::from_cbor(vec), std::out_of_range);
     }
+
+    SECTION("issue #407 - Heap-buffer-overflow (OSS-Fuzz issue 343)")
+    {
+        // original test case: incomplete float64
+        std::vector<uint8_t> vec1 {0xcb, 0x8f, 0x0a};
+        CHECK_THROWS_AS(json::from_msgpack(vec1), std::out_of_range);
+
+        // related test case: incomplete float32
+        std::vector<uint8_t> vec2 {0xca, 0x8f, 0x0a};
+        CHECK_THROWS_AS(json::from_msgpack(vec2), std::out_of_range);
+
+        // related test case: incomplete Half-Precision Float (CBOR)
+        std::vector<uint8_t> vec3 {0xf9, 0x8f};
+        CHECK_THROWS_AS(json::from_cbor(vec3), std::out_of_range);
+
+        // related test case: incomplete Single-Precision Float (CBOR)
+        std::vector<uint8_t> vec4 {0xfa, 0x8f, 0x0a};
+        CHECK_THROWS_AS(json::from_cbor(vec4), std::out_of_range);
+
+        // related test case: incomplete Double-Precision Float (CBOR)
+        std::vector<uint8_t> vec5 {0xfb, 0x8f, 0x0a};
+        CHECK_THROWS_AS(json::from_cbor(vec5), std::out_of_range);
+    }
 }