[PATCH] liquidio: avoid NULL pointer dereference in lio_vf_rep_copy_packet()

[Aleksandr Burakov <a.burakov@rosalinux.ru>]

lio_vf_rep_copy_packet() passes pg_info->page to skb_add_rx_frag()
that dereferences it without any check. So, it does not make sense
to call skb_add_rx_frag() when pg_info->page is NULL to avoid an segfault.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Aleksandr Burakov <a.burakov@rosalinux.ru>
Fixes: 1f233f327913 ("liquidio: switchdev support for LiquidIO NIC")
---
 drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
index 600de587d7a9..e70b9ccca380 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_vf_rep.c
@@ -272,13 +272,12 @@ lio_vf_rep_copy_packet(struct octeon_device *oct,
 				pg_info->page_offset;
 			memcpy(skb->data, va, MIN_SKB_SIZE);
 			skb_put(skb, MIN_SKB_SIZE);
+			skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
+					pg_info->page,
+					pg_info->page_offset + MIN_SKB_SIZE,
+					len - MIN_SKB_SIZE,
+					LIO_RXBUFFER_SZ);
 		}
-
-		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
-				pg_info->page,
-				pg_info->page_offset + MIN_SKB_SIZE,
-				len - MIN_SKB_SIZE,
-				LIO_RXBUFFER_SZ);
 	} else {
 		struct octeon_skb_page_info *pg_info =
 			((struct octeon_skb_page_info *)(skb->cb));
-- 
2.25.1