Fix data race in _PyInstruction_GetLength

Read the opcode atomically, the interpreter may be specializing it
python · Sep 10, 2024 · 837645e · 837645e
1 parent 81fe1a2
commit 837645e
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/Python/instrumentation.c b/Python/instrumentation.c
@@ -327,7 +327,8 @@ _PyInstruction_GetLength(PyCodeObject *code, int offset)
 {
     ASSERT_WORLD_STOPPED_OR_LOCKED(code);
 
-    int opcode = _PyCode_CODE(code)[offset].op.code;
+    int opcode =
+        FT_ATOMIC_LOAD_UINT8_RELAXED(_PyCode_CODE(code)[offset].op.code);
     assert(opcode != 0);
     assert(opcode != RESERVED);
     if (opcode == INSTRUMENTED_LINE) {