Don't promise that passing NULL input to Camellia works
diff --git a/include/mbedtls/camellia.h b/include/mbedtls/camellia.h
index e14a198..41e17f1 100644
--- a/include/mbedtls/camellia.h
+++ b/include/mbedtls/camellia.h
@@ -165,11 +165,9 @@
* of length \c 16 Bytes. It is updated to allow streaming
* use as explained above.
* \param input The buffer holding the input data. This must point to a
- * readable buffer of length \p length Bytes. This may be
- * \c NULL if `length == 0`.
+ * readable buffer of length \p length Bytes.
* \param output The buffer holding the output data. This must point to a
- * writable buffer of length \p length Bytes. This may be
- * \c NULL if `length == 0`.
+ * writable buffer of length \p length Bytes.
*
* \return \c 0 if successful.
* \return A negative error code on failure.
@@ -212,11 +210,9 @@
* of length \c 16 Bytes. It is updated after this call to
* allow the aforementioned streaming usage.
* \param input The buffer holding the input data. This must be a readable
- * buffer of size \p length Bytes. This may be \c NULL if
- * \p length is \c 0.
+ * buffer of size \p length Bytes.
* \param output The buffer to hold the output data. This must be a writable
- * buffer of length \p length Bytes. This may be \c NULL if
- * \p length is \c 0.
+ * buffer of length \p length Bytes.
*
* \return \c 0 if successful.
* \return A negative error code on failure.
@@ -297,11 +293,9 @@
* \param stream_block The saved stream-block for resuming. This must be a
* read/write buffer of length \c 16 Bytes.
* \param input The input data stream. This must be a readable buffer of
- * size \p length Bytes. This may be \c NULL if \p length
- * is \c 0.
+ * size \p length Bytes.
* \param output The output data stream. This must be a writable buffer
- * of size \p length Bytes. This may be \c NULL if
- * \p length is \c 0.
+ * of size \p length Bytes.
*
* \return \c 0 if successful.
* \return A negative error code on failure.