external/libyuv: Move files/fuzz to top level directory

fuzz subdirectory is not part of upstream libyuv and is specific to
android's copy of libyuv. So by moving it to the top level
external/libyuv directory, we can make sure that "files" subdirectory
contains a pristine copy of upstream libyuv.

It also makes updating libyuv from upstream easier.

Bug: 241008246
Test: libyuv_mjpeg_dec_fuzz target builds successfully

Merged-In: Iab37b2c9365725362443408f5fc493730fafcd86
Change-Id: I8684819a8069c5cd0f2b8a36824ee424cf086130

3 files changed, 165 insertions, 0 deletions

diff --git a/fuzz/Android.bp b/fuzz/Android.bp
new file mode 100644
index 00000000..a8d552b1
--- /dev/null
+++ b/fuzz/Android.bp
@@ -0,0 +1,24 @@
+
+package {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "external_libyuv_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-BSD
+    default_applicable_licenses: ["external_libyuv_license"],
+}
+
+cc_fuzz {
+    name: "libyuv_mjpeg_dec_fuzz",
+    host_supported: false,
+    srcs: [
+        "mjpeg_dec_fuzz.cc",
+    ],
+    static_libs: [
+        "libyuv",
+    ],
+
+    shared_libs: [
+        "libjpeg",
+    ],
+}
diff --git a/fuzz/OWNERS b/fuzz/OWNERS
new file mode 100644
index 00000000..37481f5d
--- /dev/null
+++ b/fuzz/OWNERS
@@ -0,0 +1,2 @@
+ispo@google.com
+fbarchard@google.com
diff --git a/fuzz/mjpeg_dec_fuzz.cc b/fuzz/mjpeg_dec_fuzz.cc
new file mode 100644
index 00000000..3be8410a
--- /dev/null
+++ b/fuzz/mjpeg_dec_fuzz.cc
@@ -0,0 +1,139 @@
+// -----------------------------------------------------------------------------
+// Fuzz Target for libyuv's mjpeg decoder.
+//
+// This fuzz target focuses on the decoding from JPEG to YUV format.
+// -----------------------------------------------------------------------------
+#include "libyuv/basic_types.h"
+#include "libyuv/mjpeg_decoder.h"
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <malloc.h>
+
+
+// -----------------------------------------------------------------------------
+// Checks whether 3 values are equal.
+//
+inline bool IsEqual(int a, int b, int  c) {
+  return (a == b && a == c);
+}
+
+// -----------------------------------------------------------------------------
+// libFuzzer's callback that is invoked upon startup.
+//
+extern "C" int LLVMFuzzerInitialize(int *unused_argc, char ***unused_argv) {
+  (void) unused_argc;  // Avoid "-Wunused-parameter" warnings.
+  (void) unused_argv;
+  // Printing this message is benefial as we can infer which fuzzer runs
+  // just by looking at the logs which are stored in the cloud.
+  printf("[*] Fuzz Target for libyuv mjpeg decoder started.\n");
+
+  return 0;
+}
+
+// -----------------------------------------------------------------------------
+// Decodes a JPEG image into a YUV format.
+//
+extern "C" bool Decode(libyuv::MJpegDecoder &decoder) {
+  // YUV colors are represented with one "luminance" component called Y
+  // and two "chrominance" components, called U and V.
+  // Planar formats use separate matrices for each of the 3 color components.
+  //
+  // If we don't have 3 components abort.
+  //
+  // NOTE: It may be possible to have 4 planes for CMYK and alpha, but it's
+  // very rare and not supported.
+  int num_planes = decoder.GetNumComponents();
+
+  if (num_planes != 3) {
+    return false;
+  }
+
+  /* NOTE: Without a jpeg corpus, we can't reach this point */
+
+  int width = decoder.GetWidth();
+  int height = decoder.GetHeight();
+  int y_width = decoder.GetComponentWidth(0);
+  int y_height = decoder.GetComponentHeight(0);
+  int u_width = decoder.GetComponentWidth(1);
+  int u_height = decoder.GetComponentHeight(1);
+  int v_width = decoder.GetComponentWidth(2);
+  int v_height = decoder.GetComponentHeight(2);
+  uint8_t *y;
+  uint8_t *u;
+  uint8_t *v;
+
+  // Make sure that width and heigh stay at decent levels (< 16K * 16K).
+  // (Y is the largest buffer).
+  if (width > (1 << 14) || height > (1 << 14)) {
+    // Ok, if this happens it's a DoS, but let's ignore it for now.
+    return false;
+  }
+
+  // Allocate stides according to the sampling type.
+  if (IsEqual(y_width, u_width, v_width) &&
+      IsEqual(y_height, u_height, v_height)) {
+    // Sampling type: YUV444.
+    y = new uint8_t[width * height];
+    u = new uint8_t[width * height];
+    v = new uint8_t[width * height];
+
+  } else if (IsEqual((y_width + 1) / 2, u_width, v_width) &&
+      IsEqual(y_height, u_height, v_height)) {
+    // Sampling type: YUV422.
+    y = new uint8_t[width * height];
+    u = new uint8_t[((width + 1) / 2) * height];
+    v = new uint8_t[((width + 1) / 2) * height];
+
+  } else if (IsEqual((y_width + 1) / 2, u_width, v_width) &&
+      IsEqual((y_height + 1) / 2, u_height, v_height)) {
+    // Sampling type: YUV420.
+    y = new uint8_t[width * height];
+    u = new uint8_t[((width + 1) / 2) * ((height + 1) / 2)];
+    v = new uint8_t[((width + 1) / 2) * ((height + 1) / 2)];
+
+  } else {
+    // Invalid sampling type.
+    return false;
+  }
+
+  uint8_t* planes[] = {y, u, v};
+
+  // Do the actual decoding. (Ignore return values).
+  decoder.DecodeToBuffers(planes, width, height);
+
+  delete[] y;
+  delete[] u;
+  delete[] v;
+
+  return true;  // Success!
+}
+
+// -----------------------------------------------------------------------------
+// libFuzzer's callback that performs the actual fuzzing.
+//
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  // Make sure that we have a minimum length (32 or something small).
+  if (size < 32) {
+      return 0;
+  }
+
+  // Create the decoder object.
+  libyuv::MJpegDecoder decoder;
+
+  // Load frame, read its headers and determine uncompress image format.
+  if (decoder.LoadFrame(data, size) == LIBYUV_FALSE) {
+    // Header parsing error. Discrad frame.
+    return 0;
+  }
+
+  // Do the actual decoding.
+  Decode(decoder);
+
+  // Unload the frame.
+  decoder.UnloadFrame();
+
+  return 0;
+}