ionic: linearize tso skb with too many frags

[ Upstream commit d2c21422323b06938b3c070361dc544f047489d7 ]

We were linearizing non-TSO skbs that had too many frags, but
we weren't checking number of frags on TSO skbs.  This could
lead to a bad page reference when we received a TSO skb with
more frags than the Tx descriptor could support.

v2: use gso_segs rather than yet another division
    don't rework the check on the nr_frags

Fixes: 0f3154e6bcb3 ("ionic: Add Tx and Rx handling")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index a81feff..909eca1 100644 (file)
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -1077,15 +1077,17 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
 {
        int sg_elems = q->lif->qtype_info[IONIC_QTYPE_TXQ].max_sg_elems;
        struct ionic_tx_stats *stats = q_to_tx_stats(q);
+       int ndescs;
        int err;
 
-       /* If TSO, need roundup(skb->len/mss) descs */
+       /* Each desc is mss long max, so a descriptor for each gso_seg */
        if (skb_is_gso(skb))
-               return (skb->len / skb_shinfo(skb)->gso_size) + 1;
+               ndescs = skb_shinfo(skb)->gso_segs;
+       else
+               ndescs = 1;
 
-       /* If non-TSO, just need 1 desc and nr_frags sg elems */
        if (skb_shinfo(skb)->nr_frags <= sg_elems)
-               return 1;
+               return ndescs;
 
        /* Too many frags, so linearize */
        err = skb_linearize(skb);
@@ -1094,8 +1096,7 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)
 
        stats->linearize++;
 
-       /* Need 1 desc and zero sg elems */
-       return 1;
+       return ndescs;
 }
 
 static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs)