Add test + re-add explicit error check

Author: pitrou

cpp/src/arrow/util/rle_encoding_internal.h

@@ -661,6 +661,10 @@ auto RleBitPackedParser::PeekImpl(Handler&& handler) const
   uint32_t run_len_type = 0;
   const auto header_bytes =
       bit_util::ParseLeadingLEB128(data_, std::min(kMaxSize, data_size_), &run_len_type);
+  if (ARROW_PREDICT_FALSE(header_bytes == 0)) {
+    // Malformed LEB128 data
+    return {0, ControlFlow::Break};
+  }
 
   const bool is_bit_packed = run_len_type & 1;
   const uint32_t count = run_len_type >> 1;

cpp/src/arrow/util/rle_encoding_test.cc

@@ -590,32 +590,38 @@ TEST(RleBitPacked, RleBitPackedParserInvalidNonPadded) {
 }
 
 TEST(RleBitPacked, RleBitPackedParserErrors) {
+  using V = std::vector<uint8_t>;
+
   // Truncated LEB128 header
   TestRleBitPackedParserError(
       /* bytes= */
-      {0x81},
+      V{0x81},
       /* bit_width= */ 3);
 
   // Invalid LEB128 header for a 32-bit value
   TestRleBitPackedParserError(
       /* bytes= */
-      {0xFF, 0xFF, 0xFF, 0xFF, 0x7f},
+      V{0xFF, 0xFF, 0xFF, 0xFF, 0x7f},
       /* bit_width= */ 3);
 
   // Zero-length repeated run
   TestRleBitPackedParserError(
       /* bytes= */
-      {0x00},
+      V{0x00, 0x00},
       /* bit_width= */ 3);
   TestRleBitPackedParserError(
       /* bytes= */
-      {0x80, 0x00},
+      V{0x80, 0x00, 0x00},
       /* bit_width= */ 3);
 
   // Zero-length bit-packed run
   TestRleBitPackedParserError(
       /* bytes= */
-      {0x01},
+      V{0x01},
+      /* bit_width= */ 3);
+  TestRleBitPackedParserError(
+      /* bytes= */
+      V{0x80, 0x01},
       /* bit_width= */ 3);
 
   // Bit-packed run too large