Fix buffer length check and add test cases

Signed-off-by: grantseltzer <[email protected]>
DataDog · Dec 21, 2024 · f0b61fb · f0b61fb
1 parent 44dd831
commit f0b61fb
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Showing 2 changed files with 29 additions and 6 deletions.
diff --git a/pkg/dynamicinstrumentation/eventparser/event_parser.go b/pkg/dynamicinstrumentation/eventparser/event_parser.go
@@ -92,19 +92,20 @@ func parseParamValue(definition *ditypes.Param, buffer []byte) (*ditypes.Param,
 	}
 
 	valueStack := newParamStack()
-	for bufferIndex+8 < len(buffer) {
+	for bufferIndex <= len(buffer) {
 		paramDefinition := definitionStack.pop()
 		if paramDefinition == nil {
 			break
 		}
 		if reflect.Kind(paramDefinition.Kind) == reflect.String {
-			if len(buffer) > bufferIndex+int(paramDefinition.Size) {
-				paramDefinition.ValueStr = string(buffer[bufferIndex : bufferIndex+int(paramDefinition.Size)])
-				bufferIndex += int(paramDefinition.Size)
+			if bufferIndex+int(paramDefinition.Size) > len(buffer) {
+				break
 			}
+			paramDefinition.ValueStr = string(buffer[bufferIndex : bufferIndex+int(paramDefinition.Size)])
+			bufferIndex += int(paramDefinition.Size)
 			valueStack.push(paramDefinition)
 		} else if !isTypeWithHeader(paramDefinition.Kind) {
-			if bufferIndex+int(paramDefinition.Size) >= len(buffer) {
+			if bufferIndex+int(paramDefinition.Size) > len(buffer) {
 				break
 			}
 			// This is a regular value (no sub-fields).
@@ -113,7 +114,7 @@ func parseParamValue(definition *ditypes.Param, buffer []byte) (*ditypes.Param,
 			bufferIndex += int(paramDefinition.Size)
 			valueStack.push(paramDefinition)
 		} else if reflect.Kind(paramDefinition.Kind) == reflect.Pointer {
-			if bufferIndex+int(paramDefinition.Size) >= len(buffer) {
+			if bufferIndex+int(paramDefinition.Size) > len(buffer) {
 				break
 			}
 			paramDefinition.Fields = append(paramDefinition.Fields, valueStack.pop())

diff --git a/pkg/dynamicinstrumentation/eventparser/event_parser_test.go b/pkg/dynamicinstrumentation/eventparser/event_parser_test.go
@@ -111,6 +111,28 @@ func TestParseParamValue(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "same sized string",
+			inputBuffer: []byte{
+				65, 65, 65,
+			},
+			inputDefinition: &ditypes.Param{
+				Type: "string", Size: 0x3, Kind: 0x18,
+			},
+			expectedValue: &ditypes.Param{
+				ValueStr: "AAA", Type: "string", Size: 0x3, Kind: 0x18,
+			},
+		},
+		{
+			name:        "empty string",
+			inputBuffer: []byte{},
+			inputDefinition: &ditypes.Param{
+				Type: "string", Size: 0x0, Kind: 0x18,
+			},
+			expectedValue: &ditypes.Param{
+				ValueStr: "", Type: "string", Size: 0x0, Kind: 0x18,
+			},
+		},
 	}
 
 	for _, tt := range tests {