Fix off-by-one loop count in MapArrayTypeName, and get rid of static array.

MapArrayTypeName would copy up to NAMEDATALEN-1 bytes of the base type
name, which of course is wrong: after prepending '_' there is only room for
NAMEDATALEN-2 bytes.  Aside from being the wrong result, this case would
lead to overrunning the statically allocated work buffer.  This would be a
security bug if the function were ever used outside bootstrap mode, but it
isn't, at least not in any currently supported branches.

Aside from fixing the off-by-one loop logic, this patch gets rid of the
static work buffer by having MapArrayTypeName pstrdup its result; the sole
caller was already doing that, so this just requires moving the pstrdup
call.  This saves a few bytes but mainly it makes the API a lot cleaner.

Back-patch on the off chance that there is some third-party code using
MapArrayTypeName with less-secure input.  Pushing pstrdup into the function
should not cause any serious problems for such hypothetical code; at worst
there might be a short term memory leak.

Per Coverity scanning.

diff --git a/src/backend/bootstrap/bootscanner.l b/src/backend/bootstrap/bootscanner.l
index f0316b8360ecd6f56ee5409cd9a043ac699e93d5..6ad8b32d99dcf407e2153dfe6c6a980bb87077ce 100644 (file)
--- a/src/backend/bootstrap/bootscanner.l
+++ b/src/backend/bootstrap/bootscanner.l
@@ -111,7 +111,7 @@ insert                      { return(INSERT_TUPLE); }
 "toast"                        { return(XTOAST); }
 
 {arrayid}              {
-                                       yylval.str = pstrdup(MapArrayTypeName(yytext));
+                                       yylval.str = MapArrayTypeName(yytext);
                                        return(ID);
                                }
 {id}                   {

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 4a542e65ca267911a21682579b3acc5dfad336ad..ed2b05a90554b7b250b70791b4eb9b7fd7676ac5 100644 (file)
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -1032,38 +1032,33 @@ AllocateAttribute(void)
        return attribute;
 }
 
-/* ----------------
+/*
  *             MapArrayTypeName
- * XXX arrays of "basetype" are always "_basetype".
- *        this is an evil hack inherited from rel. 3.1.
- * XXX array dimension is thrown away because we
- *        don't support fixed-dimension arrays.  again,
- *        sickness from 3.1.
  *
- * the string passed in must have a '[' character in it
+ * Given a type name, produce the corresponding array type name by prepending
+ * '_' and truncating as needed to fit in NAMEDATALEN-1 bytes.  This is only
+ * used in bootstrap mode, so we can get away with assuming that the input is
+ * ASCII and we don't need multibyte-aware truncation.
  *
- * the string returned is a pointer to static storage and should NOT
- * be freed by the CALLER.
- * ----------------
+ * The given string normally ends with '[]' or '[digits]'; we discard that.
+ *
+ * The result is a palloc'd string.
  */
 char *
-MapArrayTypeName(char *s)
+MapArrayTypeName(const char *s)
 {
        int                     i,
                                j;
-       static char newStr[NAMEDATALEN];        /* array type names < NAMEDATALEN long */
+       char            newStr[NAMEDATALEN];
 
-       if (s == NULL || s[0] == '\0')
-               return s;
-
-       j = 1;
        newStr[0] = '_';
-       for (i = 0; i < NAMEDATALEN - 1 && s[i] != '['; i++, j++)
+       j = 1;
+       for (i = 0; i < NAMEDATALEN - 2 && s[i] != '['; i++, j++)
                newStr[j] = s[i];
 
        newStr[j] = '\0';
 
-       return newStr;
+       return pstrdup(newStr);
 }
 
 

diff --git a/src/include/bootstrap/bootstrap.h b/src/include/bootstrap/bootstrap.h
index 24ad93dbe97ac0246ff05b2c428a781f8a07f6a5..6d8393eecf124736abdbaf5d9e5d5b445baf2292 100644 (file)
--- a/src/include/bootstrap/bootstrap.h
+++ b/src/include/bootstrap/bootstrap.h
@@ -40,7 +40,7 @@ extern void InsertOneTuple(Oid objectid);
 extern void InsertOneValue(char *value, int i);
 extern void InsertOneNull(int i);
 
-extern char *MapArrayTypeName(char *s);
+extern char *MapArrayTypeName(const char *s);
 
 extern void index_register(Oid heap, Oid ind, IndexInfo *indexInfo);
 extern void build_indices(void);