incorrect bytes() constructor usage in buf_filled_with (#3077)

CHANGELOG.md

@@ -113,6 +113,7 @@
 - fix: replace assert with isinstance guard in get_callee for invalid MethodSpec tokens @williballenthin
 - fix: assign ConfigDict to model_config in ConciseModel so extra="ignore" is actually applied @williballenthin (SURF-42)
 - fix: replace assert with isinstance guard in get_callee for invalid MethodSpec tokens @williballenthin (SURF-41)
+- fix: incorrect bytes() constructor usage in buf_filled_with @mike-hunhoff #3077
 - fix: remove redundant code related to cli loading @mike-hunhoff #3076
 
 ### capa Explorer Web

capa/features/extractors/strings.py

@@ -57,7 +57,7 @@ def buf_filled_with(buf: bytes, character: int) -> bool:
         return all(b == character for b in buf)
 
     # single big allocation, re-used each loop
-    dupe_chunk = bytes(character) * SLICE_SIZE
+    dupe_chunk = bytes([character]) * SLICE_SIZE
 
     for offset in range(0, len(buf), SLICE_SIZE):
         # bytes objects are immutable, so the slices share the underlying array,

tests/test_strings.py

@@ -34,6 +34,12 @@ def test_buf_filled_with():
     assert buf_filled_with(b"", 0x00) is False  # Empty buffer
     assert buf_filled_with(b"\x00", 0x00) is True  # Single byte
 
+    # Large buffers (exercise chunked processing)
+    assert buf_filled_with(b"A" * 5000, ord("A")) is True
+    assert buf_filled_with(b"A" * 5000 + b"B", ord("A")) is False
+    assert buf_filled_with(b"\xff" * 5000, 0xFF) is True
+    assert buf_filled_with(b"\x00" * 5000, 0x00) is True
+
 
 def test_extract_ascii_strings():
     # test empty buffer