On Tue, Aug 02, 2016 at 03:02:18PM +0300, Sagi Grimberg wrote:
> The user is allowed to call ->rx_pkt_burst() even without free
> mbufs in the pool. In this scenario we'll fail allocating a rep mbuf
> on the first iteration (where pkt is still NULL). This would cause us
> to deref a NULL pkt (reset refcount and free).
>
> Fix this by checking the pkt before freeing it.
>
> Fixes: a1bdb71a32da ("net/mlx5: fix crash in Rx")
> Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
> ---
> Changes from v1:
> - check pkt only once in case we failed to allocate a buffer
>
> drivers/net/mlx5/mlx5_rxtx.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
> index fce3381ae87a..37573668e43e 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.c
> +++ b/drivers/net/mlx5/mlx5_rxtx.c
> @@ -1572,6 +1572,14 @@ mlx5_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts,
> uint16_t pkts_n)
> rte_prefetch0(wqe);
> rep = rte_mbuf_raw_alloc(rxq->mp);
> if (unlikely(rep == NULL)) {
> + ++rxq->stats.rx_nombuf;
> + if (!pkt) {
> + /*
> + * no buffers before we even started,
> + * bail out silently.
> + */
> + break;
> + }
> while (pkt != seg) {
> assert(pkt != (*rxq->elts)[idx]);
> seg = NEXT(pkt);
> @@ -1579,7 +1587,6 @@ mlx5_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts,
> uint16_t pkts_n)
> __rte_mbuf_raw_free(pkt);
> pkt = seg;
> }
> - ++rxq->stats.rx_nombuf;
> break;
> }
> if (!pkt) {
> --
> 1.9.1
A few nit-picks from check-git-log.sh:
Wrong headline uppercase:
net/mlx5: Fix possible NULL deref in RX path
Wrong headline lowercase:
net/mlx5: Fix possible NULL deref in RX path
Missing blank line after 'Fixes' tag:
Fixes: a1bdb71a32da ("net/mlx5: fix crash in Rx")
Otherwise,
Acked-by: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
--
Adrien Mazarguil
6WIND
