Fix missing bound check

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index 7bb1727..7845080 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,8 @@
 Bugfix
    * Fix potential undefined behaviour in Camellia.
    * Fix memory leaks in PKCS#5 and PKCS#12.
+   * Stack buffer overflow if ctr_drbg_update() is called with too large
+     add_len (found by Jean-Philippe Aumasson) (not triggerable remotely).
 
 Changes
    * Blind RSA private operations even when POLARSSL_RSA_NO_CRT is defined.