On Fri, Mar 31, 2017 at 10:27:44AM -0300, Philippe Mathieu-Daudé wrote: > Hi, > > Eduardo you seem skilled regarding Coccinelle scripts, is it possible to > write one to find those overflows?
Probably not. AFAIK, Coccinelle rules are based on local code syntax only. This means it doesn't know the data type of expressions like (s->tracks). > > Peter having one more macro might help or confuses more? > > #define MULTIPLY64(a32, b32) ((int64_t)a32 * b32) > > On 03/31/2017 10:13 AM, Peter Maydell wrote: > > Coverity (CID 1307776) points out that in the multiply: > > space = to_allocate * s->tracks; > > we are trying to calculate a 64 bit result but the types > > of to_allocate and s->tracks mean that we actually calculate > > a 32 bit result. Add an explicit cast to force a 64 bit > > multiply. > > > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > > Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> > > > --- > > NB: compile-and-make-check tested only... > > --- > > block/parallels.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/block/parallels.c b/block/parallels.c > > index 4173b3f..3886c30 100644 > > --- a/block/parallels.c > > +++ b/block/parallels.c > > @@ -206,7 +206,7 @@ static int64_t allocate_clusters(BlockDriverState *bs, > > int64_t sector_num, > > } > > > > to_allocate = DIV_ROUND_UP(sector_num + *pnum, s->tracks) - idx; > > - space = to_allocate * s->tracks; > > + space = (int64_t)to_allocate * s->tracks; > > if (s->data_end + space > bdrv_getlength(bs->file->bs) >> > > BDRV_SECTOR_BITS) { > > int ret; > > space += s->prealloc_size; > > -- Eduardo