On Thu, 21 Jul 2022 at 13:07, Dr. David Alan Gilbert <dgilb...@redhat.com> wrote: > > * Peter Maydell (peter.mayd...@linaro.org) wrote: > > 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.mayd...@linaro.org> > > --- > > I haven't tried to analyse the code to see if the multiplications > > could ever actually end up overflowing, but I would assume > > probably not. > > > > migration/block.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/migration/block.c b/migration/block.c > > index 9e5aae58982..3577c815a94 100644 > > --- 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) > > Is it a problem that this is passed to bdrv_create_dirty_bitmap that > takes a uint32_t ?
Shouldn't be -- the constant value still fits within 32 bits. -- PMM
