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[libpng16] Undo another faulty attempt to defeat the compiler from

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optimizing out the the core of libpng_read_fuzzer.cc
This commit is contained in:
Glenn Randers-Pehrson 2017-09-25 03:54:22 -05:00
parent 346cbf2c2a
commit dc22583aca
1 changed files with 2 additions and 11 deletions
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13
contrib/oss-fuzz/libpng_read_fuzzer.cc
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@ -5,7 +5,7 @@
// Use of this source code is governed by a BSD-style license that may // Use of this source code is governed by a BSD-style license that may
// be found in the LICENSE file https://cs.chromium.org/chromium/src/LICENSE // be found in the LICENSE file https://cs.chromium.org/chromium/src/LICENSE
// Last changed in libpng 1.6.33beta03 [September 24, 2017] // Last changed in libpng 1.6.33beta03 [September 25, 2017]
// The modifications in 2017 by Glenn Randers-Pehrson include // The modifications in 2017 by Glenn Randers-Pehrson include
// 1. addition of a PNG_CLEANUP macro, // 1. addition of a PNG_CLEANUP macro,
@ -169,23 +169,14 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
int passes = png_set_interlace_handling(png_handler.png_ptr); int passes = png_set_interlace_handling(png_handler.png_ptr);
png_start_read_image(png_handler.png_ptr); png_start_read_image(png_handler.png_ptr);
/* prevent the optimizer from removing this code entirely */ /* To do: prevent the optimizer from removing this code entirely */
int max_sample = 0;
for (int pass = 0; pass < passes; ++pass) { for (int pass = 0; pass < passes; ++pass) {
for (png_uint_32 y = 0; y < height; ++y) { for (png_uint_32 y = 0; y < height; ++y) {
png_read_row(png_handler.png_ptr, png_read_row(png_handler.png_ptr,
static_cast<png_bytep>(png_handler.row_ptr), nullptr); static_cast<png_bytep>(png_handler.row_ptr), nullptr);
max_sample = png_handler.row_ptr[0] > max_sample ?
png_handler.row_ptr[0] : max_sample;
} }
} }
/* I hope the compiler doesn't figure out that this cannot happen */
if (max_sample > 255) {
PNG_CLEANUP
return 0;
}
png_read_end(png_handler.png_ptr, png_handler.end_info_ptr); png_read_end(png_handler.png_ptr, png_handler.end_info_ptr);
PNG_CLEANUP PNG_CLEANUP