[Qemu-devel] [PATCH] Fix integer overflow in block migration bandwidth calculation

[Avishay Traeger]

block_mig_state.reads is an int, and multiplying by BLOCK_SIZE yielded a
negative number, resulting in a negative bandwidth (running on a 32-bit
machine).  Cast to avoid.

Signed-off-by: Avishay Traeger <address@hidden>
---
 block-migration.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/block-migration.c b/block-migration.c
index 8218bac..ffc92ee 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -140,7 +140,7 @@ static inline void add_avg_read_time(int64_t time)
 static inline long double compute_read_bwidth(void)
 {
     assert(block_mig_state.total_time != 0);
-    return  (block_mig_state.reads * BLOCK_SIZE)/
block_mig_state.total_time;
+    return  ((long long)block_mig_state.reads * BLOCK_SIZE)/
block_mig_state.total_time;
 }

 static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
--
1.7.0.4