[Qemu-devel] [PATCH] block/parallels.c: avoid integer overflow in allocate_clusters()

[Peter Maydell <peter.maydell@linaro.org>]

Coverity (CID 1307776) points out that in the multiply:
  space = to_allocate * s->tracks;
we are trying to calculate a 64 bit result but the types
of to_allocate and s->tracks mean that we actually calculate
a 32 bit result. Add an explicit cast to force a 64 bit
multiply.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
NB: compile-and-make-check tested only...
---
 block/parallels.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/parallels.c b/block/parallels.c
index 4173b3f..3886c30 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -206,7 +206,7 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
     }
 
     to_allocate = DIV_ROUND_UP(sector_num + *pnum, s->tracks) - idx;
-    space = to_allocate * s->tracks;
+    space = (int64_t)to_allocate * s->tracks;
     if (s->data_end + space > bdrv_getlength(bs->file->bs) >> BDRV_SECTOR_BITS) {
         int ret;
         space += s->prealloc_size;
-- 
2.7.4