Re: [dpdk-dev] [RFC 1/2] mbuf: add a sanity check on segment metadata

[Olivier Matz <olivier.matz@6wind.com>]

Hi David,

On Mon, Aug 13, 2018 at 06:03:45PM +0200, David Marchand wrote:
> Add some basic check on the segments offset and length metadata:
> always funny to have a < 0 tailroom cast to uint16_t ;-).
> 
> Signed-off-by: David Marchand <david.marchand@6wind.com>
> ---
>  lib/librte_mbuf/rte_mbuf.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
> index e714c5a..7eeef12 100644
> --- a/lib/librte_mbuf/rte_mbuf.c
> +++ b/lib/librte_mbuf/rte_mbuf.c
> @@ -200,6 +200,8 @@ rte_mbuf_sanity_check(const struct rte_mbuf *m, int is_header)
>  	pkt_len = m->pkt_len;
>  
>  	do {
> +		if (m->data_off + m->data_len > m->buf_len)
> +			rte_panic("bad segment metadata\n");

What about spliting the test into two? This would help to clarify
the error messages. I also suggest add casts to uint32 to ensure
that there is no overflow.

		if (m->data_off_len > m->buf_len)
			rte_panic("data offset too big in mbuf segment\n");
		if ((uint32_t)m->data_off + (uint32_t)m->data_len > (uint32_t)m->buf_len)
			rte_panic("data length too big in mbuf segment\n");