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 c6fcb87d744b604f90826a36c33b92653b632803..720f9dfe2b76c284494d64f4a35114b0bb74f1ec 100644 (file)
--- a/src/backend/utils/sort/logtape.c
+++ b/src/backend/utils/sort/logtape.c
@@ -389,7 +389,7 @@ ltsGetFreeBlock(LogicalTapeSet *lts)
 {
    long       *heap = lts->freeBlocks;
    long        blocknum;
-   int         heapsize;
+   long        heapsize;
    unsigned long pos;
 
    /* freelist empty; allocate a new block */