bench: fixed ubsan implicit conversion

The benchmarks can now run much longer due to the minimum of 10ms or
directly with -min_time. With -min_time=20000 I could trigger two ubsan
errors in the benchmarks, which are fixed in this commit by using
unsigned type and adding "& 0xFF".

1 files changed, 2 insertions, 2 deletions

diff --git a/src/bench/crypto_hash.cpp b/src/bench/crypto_hash.cpp
index 7d5e3ca4ee..d36e504bfc 100644
--- a/src/bench/crypto_hash.cpp
+++ b/src/bench/crypto_hash.cpp
@@ -110,9 +110,9 @@ static void MuHash(benchmark::Bench& bench)
 {
     MuHash3072 acc;
     unsigned char key[32] = {0};
-    int i = 0;
+    uint32_t i = 0;
     bench.run([&] {
-        key[0] = ++i;
+        key[0] = ++i & 0xFF;
         acc *= MuHash3072(key);
     });
 }