From e8b3e0cdcea319abf82639edb5e074ff94c4d66c Mon Sep 17 00:00:00 2001 From: Tom Sepez Date: Fri, 8 Sep 2017 10:18:37 -0700 Subject: Fix one-second spin in fx_random.cpp Take seed generation logic from base's address_space_randomization.cc. One small tweak is to avoid the bottom three bits of a stack address and invert, to make leaking ASLR more difficult along the lines of the freelist masking in base's partition allocator. Another tweak is to mix in some more time-based information. Another tweak is to add in the times called so that rapid successive calls return different results. Bug: pdfium:891 Change-Id: I14238da15cee9c8d4ca72d79e4f7fbb26997c619 Reviewed-on: https://pdfium-review.googlesource.com/13490 Reviewed-by: Henrique Nakashima Commit-Queue: Tom Sepez --- core/fxcrt/fx_random_unittest.cpp | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 core/fxcrt/fx_random_unittest.cpp (limited to 'core/fxcrt/fx_random_unittest.cpp') diff --git a/core/fxcrt/fx_random_unittest.cpp b/core/fxcrt/fx_random_unittest.cpp new file mode 100644 index 0000000000..607f1409b7 --- /dev/null +++ b/core/fxcrt/fx_random_unittest.cpp @@ -0,0 +1,24 @@ +// Copyright 2017 PDFium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "core/fxcrt/fx_random.h" + +#include +#include + +#include "testing/gtest/include/gtest/gtest.h" + +TEST(FX_Random, GenerateMT3600times) { + // Prove this doesn't spin wait for a second each time. + // Since our global seeds are sequential, they wont't collide once + // seeded until 2^32 calls, and if the PNRG is any good, we won't + // get the same sequence from different seeds, esp. with this few + // iterations. + std::set> seen; + std::array current; + for (int i = 0; i < 3600; ++i) { + FX_Random_GenerateMT(current.data(), 16); + EXPECT_TRUE(seen.insert(current).second); + } +} -- cgit v1.2.3