Fix [[:>:]] when followed by parenthesis buffer overflow.

ChangeLog

@@ -14,6 +14,10 @@ pcre2_auto_possessify.c source.
 
 4. Fix typos in dftables.c for z/OS.
 
+5. Change 36 for 10.20 broke the handling of [[:>:]] and [[:<:]] in that 
+processing them could involve a buffer overflow if the following character was 
+an opening parenthesis.
+
 
 Version 10.20 30-June-2015
 --------------------------

src/pcre2_compile.c

@@ -3238,7 +3238,7 @@ for (; ptr < cb->end_pattern; ptr++)
     if (PRIV(strncmp_c8)(ptr+1, STRING_WEIRD_STARTWORD, 6) == 0 ||
         PRIV(strncmp_c8)(ptr+1, STRING_WEIRD_ENDWORD, 6) == 0)
       {
-      ptr += 7;
+      ptr += 6;
       break;
       }
 
@@ -3303,8 +3303,9 @@ for (; ptr < cb->end_pattern; ptr++)
       if (c == CHAR_LEFT_SQUARE_BRACKET &&
           (ptr[1] == CHAR_COLON || ptr[1] == CHAR_DOT ||
            ptr[1] == CHAR_EQUALS_SIGN) && check_posix_syntax(ptr, &ptr))
-        ptr ++;
-
+        {
+        ptr++;
+        }
       else if (c == CHAR_BACKSLASH)
         {
         errorcode = 0;

testdata/testinput2

@@ -4327,4 +4327,6 @@ a random value. /Ix
 
 /^(?:(?(1)x|)+)+$()/B
 
+/[[:>:]](?<)/
+
 # End of testinput2 

testdata/testoutput2

@@ -14470,4 +14470,7 @@ Failed: error 161 at offset 32: number is too big
         End
 ------------------------------------------------------------------
 
+/[[:>:]](?<)/
+Failed: error 124 at offset 10: unrecognized character after (?<
+
 # End of testinput2