Some security checks that we've found an external value completely

when fetching toasted values.

Jan

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index e9b071d0c0c9a0ff86ed105a1b966434dc8384eb..8abadaa7355eb5c75bbfed4ae9f071e47ef5af21 100644 (file)
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.6 2000/07/06 18:22:45 wieck Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.7 2000/07/11 12:32:03 wieck Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -929,9 +929,17 @@ toast_fetch_datum(varattrib *attr)
        Datum                                   chunk;
        bool                                    isnull;
 
+       char                               *chunks_found;
+       char                               *chunks_expected;
+
        ressize = attr->va_content.va_external.va_extsize;
     numchunks = (ressize / TOAST_MAX_CHUNK_SIZE) + 1;
 
+       chunks_found    = palloc(numchunks);
+       chunks_expected = palloc(numchunks);
+       memset(chunks_found,    0, numchunks);
+       memset(chunks_expected, 1, numchunks);
+
        result = (varattrib *)palloc(ressize + VARHDRSZ);
        VARATT_SIZEP(result) = ressize + VARHDRSZ;
        if (VARATT_IS_COMPRESSED(attr))
@@ -971,7 +979,7 @@ toast_fetch_datum(varattrib *attr)
                heap_fetch(toastrel, SnapshotAny, &toasttup, &buffer);
                pfree(indexRes);
 
-               if (!toasttup.t_data)
+               if (toasttup.t_data == NULL)
                        continue;
                ttup = &toasttup;
 
@@ -982,6 +990,20 @@ toast_fetch_datum(varattrib *attr)
                residx = (int32)heap_getattr(ttup, 2, toasttupDesc, &isnull);
                chunk = heap_getattr(ttup, 3, toasttupDesc, &isnull);
 
+               /* ----------
+                * Some checks on the data we've found
+                * ----------
+                */
+               if (residx * TOAST_MAX_CHUNK_SIZE + VARATT_SIZE(chunk) - VARHDRSZ
+                                               > ressize)
+                       elog(ERROR, "chunk data exceeds original data size for "
+                                               "toast value %d", 
+                                               attr->va_content.va_external.va_valueid);
+               if (chunks_found[residx]++ > 0)
+                       elog(ERROR, "chunk %d for toast value %d appears multiple times",
+                                               residx,
+                                               attr->va_content.va_external.va_valueid);
+
                /* ----------
                 * Copy the data into our result
                 * ----------
@@ -993,6 +1015,16 @@ toast_fetch_datum(varattrib *attr)
                ReleaseBuffer(buffer);
        }
 
+       /* ----------
+        * Final checks that we successfully fetched the datum
+        * ----------
+        */
+       if (memcmp(chunks_found, chunks_expected, numchunks) != 0)
+               elog(ERROR, "not all toast chunks found for value %d",
+                                               attr->va_content.va_external.va_valueid);
+       pfree(chunks_expected);
+       pfree(chunks_found);
+
        /* ----------
         * End scan and close relations
         * ----------