Merge remote-tracking branch 'origin/pr/2504' into mbedtls-2.7

* origin/pr/2504:
  Fix ChangeLog entry ordering
  Fix typo
  Add non-regression test for buffer overflow
  Improve documentation of mbedtls_mpi_write_string()
  Adapt ChangeLog
  Fix 1-byte buffer overflow in mbedtls_mpi_write_string()
diff --git a/ChangeLog b/ChangeLog
index a7b8c89..9d963c0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -23,6 +23,8 @@
      Christian Walther in #2239.
    * Fix potential memory leak in X.509 self test. Found and fixed by
      Junhwan Park, #2106.
+   * Fix 1-byte buffer overflow in mbedtls_mpi_write_string() when
+     used with negative inputs. Found by Guido Vranken in #2404.
 
 Changes
    * Return from various debugging routines immediately if the