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-rw-r--r--block.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/block.c b/block.c
index 7326bfeee..955eeaa7b 100644
--- a/block.c
+++ b/block.c
@@ -1636,7 +1636,19 @@ static void multiwrite_cb(void *opaque, int ret)
static int multiwrite_req_compare(const void *a, const void *b)
{
- return (((BlockRequest*) a)->sector - ((BlockRequest*) b)->sector);
+ const BlockRequest *req1 = a, *req2 = b;
+
+ /*
+ * Note that we can't simply subtract req2->sector from req1->sector
+ * here as that could overflow the return value.
+ */
+ if (req1->sector > req2->sector) {
+ return 1;
+ } else if (req1->sector < req2->sector) {
+ return -1;
+ } else {
+ return 0;
+ }
}
/*