[dpdk-dev] [PATCH] rte mempool: division or modulo by zero
Olivier Matz
olivier.matz at 6wind.com
Mon May 16 11:22:32 CEST 2016
Hi Slawomir,
On 05/12/2016 02:46 PM, Slawomir Mrozowicz wrote:
> Fix issue reported by Coverity.
>
> Coverity ID 13243: Division or modulo by zero
> In function call rte_mempool_xmem_size, division by expression total_size
> which may be zero has undefined behavior.
>
> Fixes: 148f963fb532 ("xen: core library changes")
>
> Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz at intel.com>
> ---
> lib/librte_mempool/rte_mempool.c | 18 +++++++++++-------
> 1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index f8781e1..01668c1 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -327,15 +327,19 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
> size_t
> rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz, uint32_t pg_shift)
> {
> - size_t n, pg_num, pg_sz, sz;
> + size_t n, pg_num, pg_sz;
> + size_t sz = 0;
>
> - pg_sz = (size_t)1 << pg_shift;
> + if (elt_sz > 0) {
> + pg_sz = (size_t)1 << pg_shift;
> + n = pg_sz / elt_sz;
>
> - if ((n = pg_sz / elt_sz) > 0) {
> - pg_num = (elt_num + n - 1) / n;
> - sz = pg_num << pg_shift;
> - } else {
> - sz = RTE_ALIGN_CEIL(elt_sz, pg_sz) * elt_num;
> + if (n > 0) {
> + pg_num = (elt_num + n - 1) / n;
> + sz = pg_num << pg_shift;
> + } else {
> + sz = RTE_ALIGN_CEIL(elt_sz, pg_sz) * elt_num;
> + }
> }
>
> return sz;
>
I think it would be clearer (either for the patch and the code) to avoid
an additional indent, and do something like that:
size_t
rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz,
uint32_t pg_shift)
{
if (elt_sz == 0)
return 0;
/* same code as before */
It will also facilitate the merge with
http://patchwork.dpdk.org/dev/patchwork/patch/12057/
Could you please submit a v2 with this logic?
Thanks,
Olivier
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