Fix Memory Leak

src/msgpack.zig

@@ -2847,6 +2847,7 @@ pub fn PackWithLimits(
             else
                 std.ArrayList(ParseState){};
             defer if (current_zig.minor == 14) parse_stack.deinit() else parse_stack.deinit(allocator);
+            errdefer cleanupParseStack(&parse_stack, allocator);
 
             // Root payload to return
             var root: ?Payload = null;
@@ -2861,7 +2862,6 @@ pub fn PackWithLimits(
             while (true) {
                 // Check depth limit
                 if (parse_stack.items.len >= parse_limits.max_depth) {
-                    cleanupParseStack(&parse_stack, allocator);
                     return MsgPackError.MaxDepthExceeded;
                 }
 
@@ -2903,7 +2903,6 @@ pub fn PackWithLimits(
                         // Validate string length
                         if (val.len > parse_limits.max_string_length) {
                             allocator.free(val);
-                            cleanupParseStack(&parse_stack, allocator);
                             return MsgPackError.StringTooLong;
                         }
 
@@ -2915,7 +2914,6 @@ pub fn PackWithLimits(
                         // Validate binary length
                         if (val.len > parse_limits.max_bin_length) {
                             allocator.free(val);
-                            cleanupParseStack(&parse_stack, allocator);
                             return MsgPackError.BinDataLengthTooLong;
                         }
 
@@ -2928,7 +2926,6 @@ pub fn PackWithLimits(
 
                         // Validate array length
                         if (len > parse_limits.max_array_length) {
-                            cleanupParseStack(&parse_stack, allocator);
                             return MsgPackError.ArrayTooLarge;
                         }
 
@@ -2961,7 +2958,6 @@ pub fn PackWithLimits(
 
                         // Validate map size
                         if (len > parse_limits.max_map_size) {
-                            cleanupParseStack(&parse_stack, allocator);
                             return MsgPackError.MapTooLarge;
                         }
 
@@ -2975,7 +2971,6 @@ pub fn PackWithLimits(
                             errdefer if (!map_owned) map.deinit();
 
                             const capacity = std.math.cast(u32, len) orelse {
-                                cleanupParseStack(&parse_stack, allocator);
                                 return MsgPackError.MapTooLarge;
                             };
                             try map.ensureTotalCapacity(capacity);

src/test.zig

@@ -125,6 +125,50 @@ test "PackerIO: corrupted length field" {
     }
 }
 
+test "PackerIO: truncated array cleanup" {
+    if (!has_new_io) return error.SkipZigTest;
+
+    // Test that truncated array data is properly cleaned up on error
+    // This demonstrates the benefit of errdefer cleanupParseStack
+    var buffer: [50]u8 = undefined;
+    var input = if (builtin.zig_version.minor == 14)
+        std.ArrayList(u8).init(allocator)
+    else
+        std.ArrayList(u8){};
+    defer if (builtin.zig_version.minor == 14) input.deinit() else input.deinit(allocator);
+
+    // Create array header for 3 elements (0x93)
+    if (builtin.zig_version.minor == 14) {
+        try input.append(0x93); // fixarray with 3 elements
+        try input.append(0x01); // first element: uint 1
+        try input.append(0x02); // second element: uint 2
+        // Missing third element - truncated!
+    } else {
+        try input.append(allocator, 0x93);
+        try input.append(allocator, 0x01);
+        try input.append(allocator, 0x02);
+    }
+
+    @memcpy(buffer[0..input.items.len], input.items);
+
+    var writer = std.Io.Writer.fixed(&buffer);
+    var reader = std.Io.Reader.fixed(buffer[0..input.items.len]);
+
+    var packer = msgpack.PackerIO.init(&reader, &writer);
+
+    // Should fail due to truncated data (missing third element)
+    const result = packer.read(allocator);
+    if (result) |payload| {
+        payload.free(allocator);
+        try expect(false); // Should not succeed with truncated array
+    } else |err| {
+        // Expected error - truncated array cannot be fully read
+        try expect(err == msgpack.MsgPackError.TypeMarkerReading or
+            err == msgpack.MsgPackError.DataReading or
+            err == error.EndOfStream);
+    }
+}
+
 test "PackerIO: multiple payloads with error recovery" {
     if (!has_new_io) return error.SkipZigTest;