1 files changed, 6 insertions, 0 deletions
diff --git a/source/text.cpp b/source/text.cpp
index 88a8e8ff..415c059d 100644
--- a/source/text.cpp
+++ b/source/text.cpp
@@ -715,6 +715,12 @@ spv_result_t GetNumericIds(const spvtools::AssemblyGrammar& grammar,
   while (context.hasText()) {
     spv_instruction_t inst;
 
+    // Operand parsing sometimes involves knowing the opcode of the instruction
+    // being parsed. A malformed input might feature such an operand *before*
+    // the opcode is known. To guard against accessing an uninitialized opcode,
+    // the instruction's opcode is initialized to a default value.
+    inst.opcode = SpvOpMax;
+
     if (spvTextEncodeOpcode(grammar, &context, &inst)) {
       return SPV_ERROR_INVALID_TEXT;
     }