[PATCH 1/7] block/vdi.c: Avoid potential overflow when calculating size of write

[Peter Maydell]

In vdi_co_pwritev() we multiply a sector count by SECTOR_SIZE to
get the size to write in bytes. Coverity notes that this means that
we do the multiply as a 32x32->32 multiply before converting to
64 bits, which has the potential to overflow.

This is very unlikely to happen, since the block map has 4 bytes per
block and the maximum number of blocks in the image must fit into a
32-bit integer.  But we can keep Coverity happy by including a cast
so we do a 64-bit multiply here.

Resolves: Coverity CID 1508076
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 block/vdi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vdi.c b/block/vdi.c
index 6363da08cee..27c60ba18d0 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -728,7 +728,7 @@ nonallocating_write:
         logout("will write %u block map sectors starting from entry %u\n",
                n_sectors, bmap_first);
         ret = bdrv_co_pwrite(bs->file, bmap_offset * SECTOR_SIZE,
-                             n_sectors * SECTOR_SIZE, base, 0);
+                             n_sectors * (uint64_t)SECTOR_SIZE, base, 0);
     }
 
     return ret;
-- 
2.34.1