usbredirparserfuzz: Use constant for magic number

Now that the magic number for the serialization format is a header it can also
be used for fuzzing. As it turned out I had gotten the endianess wrong in commit
58f198e and the unserialization code wasn't actually fuzzed (unless the fuzzer
had somehow found the magic value).

Endianess support is still in the TODO file and so a plain memcpy is sufficient.

Signed-off-by: Michael Hanselmann <public@hansmi.ch>

1 files changed, 6 insertions, 3 deletions

diff --git a/fuzzing/usbredirparserfuzz.cc b/fuzzing/usbredirparserfuzz.cc
index 6fb16c8..78073f3 100644
--- a/fuzzing/usbredirparserfuzz.cc
+++ b/fuzzing/usbredirparserfuzz.cc
@@ -20,6 +20,7 @@
 #include <algorithm>
 #include <memory>
 
+#include <cassert>
 #include <cinttypes>
 #include <cstring>
 #include <limits>
@@ -255,9 +256,11 @@ int try_unserialize(struct usbredirparser *parser, FuzzedDataProvider *fdp)
     state.reserve(len);
 
     if (len >= 4) {
-        // Could also move USBREDIRPARSER_SERIALIZE_MAGIC after moving it to
-        // a shared header.
-        state.insert(state.end(), {'U', 'R', 'P', '1'});
+        const uint32_t magic = USBREDIRPARSER_SERIALIZE_MAGIC;
+        assert(state.empty());
+        state.resize(sizeof(magic));
+        memcpy(state.data(), &magic, sizeof(magic));
+
         len -= 4;
     }