Fix array overrun in ecpg's version of ParseDateTime().

tglsfdc · tglsfdc · commit d9a1e9de5474 · 2014-10-06T21:23:50.000-04:00
The code wrote a value into the caller's field[] array before checking to see if there was room, which of course is backwards. Per report from Michael Paquier. I fixed the equivalent bug in the backend's version of this code way back in 630684d, but failed to think about ecpg's copy. Fortunately this doesn't look like it would be exploitable for anything worse than a core dump: an external attacker would have no control over the single word that gets written.
diff --git a/src/interfaces/ecpg/pgtypeslib/dt_common.c b/src/interfaces/ecpg/pgtypeslib/dt_common.c
@@ -1672,6 +1672,7 @@ DecodePosixTimezone(char *str, int *tzp)
  *
  * The "lowstr" work buffer must have at least strlen(timestr) + MAXDATEFIELDS
  * bytes of space.  On output, field[] entries will point into it.
+ * The field[] and ftype[] arrays must have at least MAXDATEFIELDS entries.
  */
 int
 ParseDateTime(char *timestr, char *lowstr,
@@ -1685,9 +1686,9 @@ ParseDateTime(char *timestr, char *lowstr,
 	while (*(*endstr) != '\0')
 	{
 		/* Record start of current field */
-		field[nf] = lp;
 		if (nf >= MAXDATEFIELDS)
 			return -1;
+		field[nf] = lp;
 
 		/* leading digit? then date or time */
 		if (isdigit((unsigned char) *(*endstr)))
