[Qemu-devel] [PATCH 75/88] qcow2: Prevent numerical overflow

[Michael Roth]

From: Max Reitz <address@hidden>

In qcow2_alloc_cluster_offset(), *num is limited to
INT_MAX >> BDRV_SECTOR_BITS by all callers. However, since remaining is
of type uint64_t, we might as well cast *num to that type before
performing the shift.

Cc: address@hidden
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
(cherry picked from commit 11c89769dc3e638ef72915d97058411ddf79b64b)
Signed-off-by: Michael Roth <address@hidden>
---
 block/qcow2-cluster.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 26827a2..769e68d 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1202,7 +1202,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, 
uint64_t offset,
 
 again:
     start = offset;
-    remaining = *num << BDRV_SECTOR_BITS;
+    remaining = (uint64_t)*num << BDRV_SECTOR_BITS;
     cluster_offset = 0;
     *host_offset = 0;
     cur_bytes = 0;
-- 
1.9.1