Bugs: #7111: server crashes when regexp is used

1 files changed, 19 insertions, 2 deletions

diff --git a/regex/regcomp.c b/regex/regcomp.c
index 5f0351c32aa..998b39379aa 100644
--- a/regex/regcomp.c
+++ b/regex/regcomp.c
@@ -860,11 +860,28 @@ othercase(charset,ch)
 CHARSET_INFO *charset;
 int ch;
 {
+	/*
+	  In MySQL some multi-byte character sets
+	  have 'ctype' array but don't have 'to_lower'
+	  and 'to_upper' arrays. In this case we handle
+	  only basic latin letters a..z and A..Z.
+	  
+	  If 'to_lower' and 'to_upper' arrays are empty in a character set,
+	  then my_isalpha(cs, ch) should never return TRUE for characters
+	  other than basic latin letters. Otherwise it should be
+	  considered as a mistake in character set definition.
+	*/
 	assert(my_isalpha(charset,ch));
 	if (my_isupper(charset,ch))
-		return(my_tolower(charset,ch));
+	{
+		return(charset->to_lower ? my_tolower(charset,ch) :
+		                          ch - 'A' + 'a');
+	}
 	else if (my_islower(charset,ch))
-		return(my_toupper(charset,ch));
+	{
+		return(charset->to_upper ? my_toupper(charset,ch) :
+		                          ch - 'a' + 'A');
+	}
 	else			/* peculiar, but could happen */
 		return(ch);
 }