Limit the size of images being fuzzed in XFACodecFuzzers

This limits the size detected in the header to 1,000,000 pixels, which
will support 1000 x 1000 images. This is being done to remove
non-useful OOM reports for very large images and improve fuzzing
efficiency, since larger images are unlikely to cover new logic.

BUG=pdfium:925

Change-Id: I4a7fa7cf02cbb469048b752d45bc9f64a1b60a98
Reviewed-on: https://pdfium-review.googlesource.com/17010
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

1 files changed, 10 insertions, 2 deletions

diff --git a/testing/libfuzzer/xfa_codec_fuzzer.h b/testing/libfuzzer/xfa_codec_fuzzer.h
index a590596dcf..e91ea20577 100644
--- a/testing/libfuzzer/xfa_codec_fuzzer.h
+++ b/testing/libfuzzer/xfa_codec_fuzzer.h
@@ -17,6 +17,10 @@
 #include "testing/fx_string_testhelpers.h"
 #include "third_party/base/ptr_util.h"
 
+// Arbitrarily picked to support up to 1000x1000 images. This is far below where
+// OOM issues are occuring.
+const int kXFACodecFuzzerPixelLimit = 1000000;
+
 class XFACodecFuzzer {
  public:
   static int Fuzz(const uint8_t* data, size_t size, FXCODEC_IMAGE_TYPE type) {
@@ -33,14 +37,18 @@ class XFACodecFuzzer {
     if (status != FXCODEC_STATUS_FRAME_READY)
       return 0;
 
+    // Skipping very large images, since they will take a long time and may lead
+    // to OOM.
+    if (decoder->GetWidth() * decoder->GetHeight() > kXFACodecFuzzerPixelLimit)
+      return 0;
+
     auto bitmap = pdfium::MakeRetain<CFX_DIBitmap>();
     bitmap->Create(decoder->GetWidth(), decoder->GetHeight(), FXDIB_Argb);
 
     int32_t frames;
     if (decoder->GetFrames(&frames) != FXCODEC_STATUS_DECODE_READY ||
-        frames == 0) {
+        frames == 0)
       return 0;
-    }
 
     status = decoder->StartDecode(bitmap, 0, 0, bitmap->GetWidth(),
                                   bitmap->GetHeight());