From 7e606a2d5ca59dbd901b7c8909214a0fc12fbadd Mon Sep 17 00:00:00 2001 From: Varun Gupta Date: Wed, 19 Dec 2018 10:34:30 +0530 Subject: MDEV-17589: Stack-buffer-overflow with indexed varchar (utf8) field Create a new constant MAX_DATA_LENGTH_FOR_KEY. Replace the value of MAX_KEY_LENGTH to also include the LENGTH and NULL BYTES of a field. --- sql/sql_const.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'sql/sql_const.h') diff --git a/sql/sql_const.h b/sql/sql_const.h index c37d8dd68f7..c0b343c6ca4 100644 --- a/sql/sql_const.h +++ b/sql/sql_const.h @@ -33,7 +33,17 @@ #define MAX_SYS_VAR_LENGTH 32 #define MAX_KEY MAX_INDEXES /* Max used keys */ #define MAX_REF_PARTS 32 /* Max parts used as ref */ -#define MAX_KEY_LENGTH 3072 /* max possible key */ + +/* + Maximum length of the data part of an index lookup key. + + The "data part" is defined as the value itself, not including the + NULL-indicator bytes or varchar length bytes ("the Extras"). We need this + value because there was a bug where length of the Extras were not counted. + + You probably need MAX_KEY_LENGTH, not this constant. +*/ +#define MAX_DATA_LENGTH_FOR_KEY 3072 #if SIZEOF_OFF_T > 4 #define MAX_REFLENGTH 8 /* Max length for record ref */ #else -- cgit v1.2.1