[libfuzzer] Prevent division by zero in libpng_read_fuzzer.

testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc

Index: testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc
diff --git a/testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc b/testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc
index 8599f4b0c69b58a99f28bfb802221a8dedf90575..ca9b0427bef2ce2f16605947f5ddeb01e37f611f 100644
--- a/testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc
+++ b/testing/libfuzzer/fuzzers/libpng_read_fuzzer.cc
@@ -92,7 +92,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   }
 
   // This is going to be too slow.
-  if (height > 100000000 / width)
+  if (width && height > 100000000 / width)

[aizatsky, 2016/03/18 17:18:18]

Is this written to prevent overflow? width * height > ... would look much nicer.

[mmoroz, 2016/03/21 09:07:37]

Yes, this is for overflow prevention (from here:
https://codereview.chromium.org/1808123004/).
I can replace it with cast to uint64_t, if you think it would be better.

     return 0;
 
   int passes = png_set_interlace_handling(png_ptr);