1 files changed, 52 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/fuzzer/divide.cpp b/comm/third_party/botan/src/fuzzer/divide.cpp
new file mode 100644
index 0000000000..b6342ff7d8
--- /dev/null
+++ b/comm/third_party/botan/src/fuzzer/divide.cpp
@@ -0,0 +1,52 @@
+/*
+* (C) 2015,2016,2018 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+#include "fuzzers.h"
+#include <botan/divide.h>
+
+void fuzz(const uint8_t in[], size_t len)
+   {
+   if(len % 2 == 1 || len > 2*4096/8)
+      return;
+
+   // Save on allocations by making these static
+   static Botan::BigInt x, y, q, r, ct_q, ct_r, z;
+
+   x = Botan::BigInt::decode(in, len / 2);
+   y = Botan::BigInt::decode(in + len / 2, len / 2);
+
+   if(y == 0)
+      return;
+
+   Botan::divide(x, y, q, r);
+
+   FUZZER_ASSERT_TRUE(r < y);
+
+   z = q*y + r;
+
+   FUZZER_ASSERT_EQUAL(z, x);
+
+   Botan::ct_divide(x, y, ct_q, ct_r);
+
+   FUZZER_ASSERT_EQUAL(q, ct_q);
+   FUZZER_ASSERT_EQUAL(r, ct_r);
+
+   // Now divide by just low byte of y
+
+   y = y.byte_at(0);
+   if(y == 0)
+      y = 251;
+   Botan::divide(x, y, q, r);
+
+   z = q*y + r;
+   FUZZER_ASSERT_EQUAL(z, x);
+
+   uint8_t r8;
+   Botan::ct_divide_u8(x, y.byte_at(0), ct_q, r8);
+   FUZZER_ASSERT_EQUAL(ct_q, q);
+   FUZZER_ASSERT_EQUAL(r8, r.byte_at(0));
+
+   }
+