Avoid possible overflow with ltsGetFreeBlock() in logtape.c

nFreeBlocks, defined as a long, stores the number of free blocks in a
logical tape.  ltsGetFreeBlock() has been using an int to store the
value of nFreeBlocks, which could lead to overflows on platforms where
long and int are not the same size (in short everything except Windows
where long is 4 bytes).

The problematic intermediate variable is switched to be a long instead
of an int.

Issue introduced by c02fdc9223015, so backpatch down to 13.

Author: Ranier vilela
Reviewed-by: Peter Geoghegan, David Rowley
Discussion: https://postgr.es/m/CAEudQApLDWCBR_xmwNjGBrDo+f+S4E87x3s7-+hoaKqYdtC4JQ@mail.gmail.com
Backpatch-through: 13

diff --git a/src/backend/utils/sort/logtape.c b/src/backend/utils/sort/logtape.c
index 52b8898d5edb4d4ca7e2141d6903cdb8928c2d39..f31878bdee1aec441bd1f80e10266eed1907c9c9 100644 (file)
--- a/src/backend/utils/sort/logtape.c
+++ b/src/backend/utils/sort/logtape.c
@@ -372,7 +372,7 @@ ltsGetFreeBlock(LogicalTapeSet *lts)
 {
    long       *heap = lts->freeBlocks;
    long        blocknum;
-   int         heapsize;
+   long        heapsize;
    long        holeval;
    unsigned long holepos;