[PATCH v4 03/16] block: fix theoretical overflow in bdrv_init_padding()

[Vladimir Sementsov-Ogievskiy]

Calculation of sum may theoretically overflow, so use 64bit type and
add some good assertions.

Use int64_t constantly.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/io.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/io.c b/block/io.c
index 21e8a50725..d9bc67f1b0 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1537,8 +1537,12 @@ static bool bdrv_init_padding(BlockDriverState *bs,
                               int64_t offset, int64_t bytes,
                               BdrvRequestPadding *pad)
 {
-    uint64_t align = bs->bl.request_alignment;
-    size_t sum;
+    int64_t align = bs->bl.request_alignment;
+    int64_t sum;
+
+    bdrv_check_request(offset, bytes, &error_abort);
+    assert(align <= INT_MAX); /* documented in block/block_int.h */
+    assert(align * 2 <= SIZE_MAX); /* so we can allocate the buffer */
 
     memset(pad, 0, sizeof(*pad));
 
-- 
2.25.4