Avoid undefined operation in rotation operations

2 files changed, 15 insertions, 0 deletions

diff --git a/doc/relnotes/1_11_5.rst b/doc/relnotes/1_11_5.rst
new file mode 100644
index 000000000..f554283ca
--- /dev/null
+++ b/doc/relnotes/1_11_5.rst
@@ -0,0 +1,11 @@
+Version 1.11.5, Not Yet Released
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+* TLS channels now support sending a ``std::vector``
+
+* Add a generic 64-bit multiply instruction for producing a 128 bit result
+  in mul128.h
+
+* Avoid potentially undefined operations in the bit rotation operations.  Not
+  known to have caused problems under existing compilers but might break in the
+  future. Found by Clang sanitizer, reported by Jeffrey Walton.
diff --git a/src/utils/rotate.h b/src/utils/rotate.h
index 465746e0b..2593010b4 100644
--- a/src/utils/rotate.h
+++ b/src/utils/rotate.h
@@ -20,6 +20,8 @@ namespace Botan {
 */
 template<typename T> inline T rotate_left(T input, size_t rot)
    {
+   if(rot == 0)
+      return input;
    return static_cast<T>((input << rot) | (input >> (8*sizeof(T)-rot)));;
    }
 
@@ -31,6 +33,8 @@ template<typename T> inline T rotate_left(T input, size_t rot)
 */
 template<typename T> inline T rotate_right(T input, size_t rot)
    {
+   if(rot == 0)
+      return input;
    return static_cast<T>((input >> rot) | (input << (8*sizeof(T)-rot)));
    }