From 959ac9ef804b0c7f27bce35b6c7ad9cb829098ce Mon Sep 17 00:00:00 2001
From: Alex Hultman <alexhultman@gmail.com>
Date: Fri, 14 Aug 2020 16:34:14 +0200
Subject: [PATCH] Simplify PerMessageDeflate fuzzing regions

---
 fuzzing/PerMessageDeflate.cpp | 83 ++++++++++++++++++-----------------
 1 file changed, 43 insertions(+), 40 deletions(-)

diff --git a/fuzzing/PerMessageDeflate.cpp b/fuzzing/PerMessageDeflate.cpp
index dd5afe2..3aea55e 100644
--- a/fuzzing/PerMessageDeflate.cpp
+++ b/fuzzing/PerMessageDeflate.cpp
@@ -4,6 +4,7 @@
 
 #include <cstdio>
 #include <string>
+#include <bitset>
 
 /* We test the permessage deflate module */
 #include "../src/PerMessageDeflate.h"
@@ -13,48 +14,50 @@
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 
     /* First byte determines what compressor to use */
-    if (size < 1) {
-        return 0;
+    if (size >= 1) {
+
+        int compressors[] = {
+            uWS::DEDICATED_COMPRESSOR_3KB,
+            uWS::DEDICATED_COMPRESSOR_4KB,
+            uWS::DEDICATED_COMPRESSOR_8KB,
+            uWS::DEDICATED_COMPRESSOR_16KB,
+            uWS::DEDICATED_COMPRESSOR_32KB,
+            uWS::DEDICATED_COMPRESSOR_64KB,
+            uWS::DEDICATED_COMPRESSOR_128KB,
+            uWS::DEDICATED_COMPRESSOR_256KB
+        };
+
+        auto compressor = compressors[data[0] % 8];
+        data++;
+        size--;
+
+        /* Bits 0 - 256 are okay */
+        std::bitset<257> b;
+
+        /* If we could specify LARGE_BUFFER_SIZE small here we could force it to inflate in chunks,
+        * triggering more line coverage. Currently it is set to 16kb which is always too much */
+        struct StaticData {
+            uWS::DeflationStream deflationStream;
+            uWS::ZlibContext zlibContext;
+
+            uWS::InflationStream inflationStream;
+        } staticData = {compressor};
+
+        /* Why is this padded? */
+        makeChunked(makePadded(data, size), size, [&staticData, &b](const uint8_t *data, size_t size) {
+            auto [inflation, valid] = staticData.inflationStream.inflate(&staticData.zlibContext, std::string_view((char *) data, size), 256);
+
+            /* Trigger ASAN flaws if length is more than 256 */
+            b.set(inflation.length());
+        });
+
+        makeChunked(makePadded(data, size), size, [&staticData](const uint8_t *data, size_t size) {
+            /* Always reset */
+            staticData.deflationStream.deflate(&staticData.zlibContext, std::string_view((char *) data, size), true);
+        });
+
     }
 
-    int compressors[] = {
-        uWS::DEDICATED_COMPRESSOR_3KB,
-        uWS::DEDICATED_COMPRESSOR_4KB,
-        uWS::DEDICATED_COMPRESSOR_8KB,
-        uWS::DEDICATED_COMPRESSOR_16KB,
-        uWS::DEDICATED_COMPRESSOR_32KB,
-        uWS::DEDICATED_COMPRESSOR_64KB,
-        uWS::DEDICATED_COMPRESSOR_128KB,
-        uWS::DEDICATED_COMPRESSOR_256KB
-    };
-
-    auto compressor = compressors[data[0] % 8];
-    data++;
-    size--;
-
-    /* If we could specify LARGE_BUFFER_SIZE small here we could force it to inflate in chunks,
-     * triggering more line coverage. Currently it is set to 16kb which is always too much */
-    struct StaticData {
-        uWS::DeflationStream deflationStream;
-        uWS::ZlibContext zlibContext;
-
-        uWS::InflationStream inflationStream;
-    } staticData = {compressor};
-
-    /* Why is this padded? */
-    makeChunked(makePadded(data, size), size, [&staticData](const uint8_t *data, size_t size) {
-        auto [inflation, valid] = staticData.inflationStream.inflate(&staticData.zlibContext, std::string_view((char *) data, size), 256);
-        if (inflation.length() > 256) {
-            /* Cause ASAN to freak out */
-            delete (int *) (void *) 1;
-        }
-    });
-
-    makeChunked(makePadded(data, size), size, [&staticData](const uint8_t *data, size_t size) {
-        /* Always reset */
-        staticData.deflationStream.deflate(&staticData.zlibContext, std::string_view((char *) data, size), true);
-    });
-
     return 0;
 }