RE: [PATCH] ring: fix overflow in memory size calcuation

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Liang Ma [mailto:liangma@liangbit.com]
> Sent: Wednesday, 15 December 2021 09.01
> 
> On Tue, Dec 14, 2021 at 11:30:16AM +0800, Zhihong Wang wrote:
> > Parameters count and esize are both unsigned int, and their product
> can
> > legally exceed unsigned int and lead to runtime access violation.
> >
> > Fixes: cc4b218790f6 ("ring: support configurable element size")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Zhihong Wang <wangzhihong.wzh@bytedance.com>
> > ---
> >  lib/ring/rte_ring.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c
> > index f17bd966be..d1b80597af 100644
> > --- a/lib/ring/rte_ring.c
> > +++ b/lib/ring/rte_ring.c
> > @@ -75,7 +75,7 @@ rte_ring_get_memsize_elem(unsigned int esize,
> unsigned int count)
> >  		return -EINVAL;
> >  	}
> >
> > -	sz = sizeof(struct rte_ring) + count * esize;
> > +	sz = sizeof(struct rte_ring) + (ssize_t)count * esize;
> >  	sz = RTE_ALIGN(sz, RTE_CACHE_LINE_SIZE);
> >  	return sz;
> >  }
> > --
> > 2.11.0
> >
> Reviewed-by Liang Ma <liangma@liangbit.com>

I was wondering about the type conversion to signed (instead of unsigned), but sz is ssize_t, so the conversion to ssize_t is correct. Otherwise, sz should be changed from ssize_t to size_t too.

No need for further changes.

Reviewed-by: Morten Brørup <mb@smartsharesystems.com>