tdb: add overflow detection to tdb_expand_adjust()

We round up at maximun to a new size of 4GB,
but still return at least the given size.

The caller has to deal with ENOSPC itself.

Pair-Programmed-With: Volker Lendecke <vl@samba.org>

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/lib/tdb/common/io.c b/lib/tdb/common/io.c
index d17764008f613be9111411427d70f25c9a2dbf26..c9c9fa8dc9399537429f9ea630603973a3865b0d 100644 (file)
--- a/lib/tdb/common/io.c
+++ b/lib/tdb/common/io.c
@@ -363,14 +363,32 @@ static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t ad
 /* You need 'size', this tells you how much you should expand by. */
 tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size)
 {
-       tdb_off_t new_size, top_size;
+       tdb_off_t new_size, top_size, increment;
+       tdb_off_t max_size = UINT32_MAX - map_size;
+
+       if (size > max_size) {
+               /*
+                * We can't round up anymore, just give back
+                * what we're asked for.
+                *
+                * The caller has to take care of the ENOSPC handling.
+                */
+               return size;
+       }
 
        /* limit size in order to avoid using up huge amounts of memory for
         * in memory tdbs if an oddball huge record creeps in */
        if (size > 100 * 1024) {
-               top_size = map_size + size * 2;
+               increment = size * 2;
        } else {
-               top_size = map_size + size * 100;
+               increment = size * 100;
+       }
+       if (increment < size) {
+               goto overflow;
+       }
+
+       if (!tdb_add_off_t(map_size, increment, &top_size)) {
+               goto overflow;
        }
 
        /* always make room for at least top_size more records, and at
@@ -381,10 +399,20 @@ tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size)
        } else {
                new_size = map_size * 1.25;
        }
+       if (new_size < map_size) {
+               goto overflow;
+       }
 
        /* Round the database up to a multiple of the page size */
        new_size = MAX(top_size, new_size);
        return TDB_ALIGN(new_size, page_size) - map_size;
+
+overflow:
+       /*
+        * Somewhere in between we went over 4GB. Make one big jump to
+        * exactly 4GB database size.
+        */
+       return max_size;
 }
 
 /* expand the database at least size bytes by expanding the underlying