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 b97414c7518b35236b7f5321b8452ea6c9a63aa1..c361e47cee38c050039877c822698398233b257c 100644 (file)
--- a/src/backend/utils/sort/logtape.c
+++ b/src/backend/utils/sort/logtape.c
@@ -391,7 +391,7 @@ ltsGetFreeBlock(LogicalTapeSet *lts)
 {
    long       *heap = lts->freeBlocks;
    long        blocknum;
-   int         heapsize;
+   long        heapsize;
    unsigned long pos;
 
    /* freelist empty; allocate a new block */