migration: Define BLK_MIG_BLOCK_SIZE as unsigned long long

When we use BLK_MIG_BLOCK_SIZE in expressions like
block_mig_state.submitted * BLK_MIG_BLOCK_SIZE, this multiplication
is done as 32 bits, because both operands are 32 bits.  Coverity
complains about possible overflows because we then accumulate that
into a 64 bit variable.

Define BLK_MIG_BLOCK_SIZE as unsigned long long using the ULL suffix.
The only two current uses of it with this problem are both in
block_save_pending(), so we could just cast to uint64_t there, but
using the ULL suffix is simpler and ensures that we don't
accidentally introduce new variants of the same issue in future.

Resolves: Coverity CID 1487136, 1487175
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220721115207.729615-3-peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/migration/block.c b/migration/block.c
index 9e5aae5898256abeedc98915758a56b3b465e938..3577c815a947b62286c635d45f108fdfec2e470e 100644 (file)
--- a/migration/block.c
+++ b/migration/block.c
@@ -28,7 +28,7 @@
 #include "sysemu/block-backend.h"
 #include "trace.h"
 
-#define BLK_MIG_BLOCK_SIZE           (1 << 20)
+#define BLK_MIG_BLOCK_SIZE           (1ULL << 20)
 #define BDRV_SECTORS_PER_DIRTY_CHUNK (BLK_MIG_BLOCK_SIZE >> BDRV_SECTOR_BITS)
 
 #define BLK_MIG_FLAG_DEVICE_BLOCK       0x01