ROB: Guard ArrayObject.read_from_stream against uncaught RecursionError

pypdf/generic/_data_structures.py

@@ -300,7 +300,18 @@ def read_from_stream(
                 stream.seek(-len(rest), 1)
             stream.seek(-1, 1)
             # read and append object
-            arr.append(read_object(stream, pdf, forced_encoding, parsing_budget=parsing_budget))
+            try:
+                obj = read_object(stream, pdf, forced_encoding, parsing_budget=parsing_budget)
+            except LimitReachedError:
+                # Always propagate security issues.
+                raise
+            except (MemoryError, RecursionError) as exc:
+                # A deeply nested array (e.g. "[[[[...]]]]") blows the interpreter's
+                # recursion limit before the element-count budget above ever triggers,
+                # since nesting depth, not element count, drives the recursion here.
+                # Mirrors the guard DictionaryObject.read_from_stream already applies.
+                raise PdfReadError("Error reading PDF file.") from exc
+            arr.append(obj)
         return arr
 
 

tests/generic/test_data_structures.py

@@ -807,6 +807,17 @@ def test_array_object__read_from_stream__maximum_element_count() -> None:
             ArrayObject.read_from_stream(BytesIO(data), pdf=pdf)  # type: ignore[arg-type]
 
 
+def test_array_object__read_from_stream__deeply_nested_array_raises_pdfreaderror() -> None:
+    # A single array nested thousands of levels deep drives recursion depth,
+    # not element count, so array_maximum_element_count never engages.
+    # Previously this raised an uncaught RecursionError instead of PdfReadError.
+    pdf = ReaderDummy()
+    depth = 5000
+    data = b"[" * depth + b"]" * depth
+    with pytest.raises(PdfReadError, match=r"^Error reading PDF file\.$"):
+        ArrayObject.read_from_stream(BytesIO(data), pdf=pdf)  # type: ignore[arg-type]
+
+
 def test_dictionary_object__read_from_stream__token_limit() -> None:
     pdf = ReaderDummy()
     data = b"<< /Key1 << /Key2 << /Key3 << /Key4 << /SomeName 42 >> >> >> >> /Key5 13 >>"