[PATCH] octeon_ep_vf: add NULL check for napi_build_skb()

[David Carlier <devnexen@gmail.com>]

napi_build_skb() can return NULL on allocation failure. In
__octep_vf_oq_process_rx(), the result is used directly without a NULL
check in both the single-buffer and multi-fragment paths, leading to a
NULL pointer dereference.

Add NULL checks after both napi_build_skb() calls, properly advancing
descriptors and consuming remaining fragments on failure.

Fixes: 1cd3b407977c ("octeon_ep_vf: add Tx/Rx processing and interrupt support")
Cc: stable@vger.kernel.org
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 .../marvell/octeon_ep_vf/octep_vf_rx.c        | 34 ++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
index b579d5b545c4..97b836c1f5d2 100644
--- a/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
+++ b/drivers/net/ethernet/marvell/octeon_ep_vf/octep_vf_rx.c
@@ -409,10 +409,18 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
 			data_offset = OCTEP_VF_OQ_RESP_HW_SIZE;
 			rx_ol_flags = 0;
 		}
-		rx_bytes += buff_info->len;
 
 		if (buff_info->len <= oq->max_single_buffer_size) {
 			skb = napi_build_skb((void *)resp_hw, PAGE_SIZE);
+			if (!skb) {
+				oq->stats->alloc_failures++;
+				read_idx++;
+				desc_used++;
+				if (read_idx == oq->max_count)
+					read_idx = 0;
+				continue;
+			}
+			rx_bytes += buff_info->len;
 			skb_reserve(skb, data_offset);
 			skb_put(skb, buff_info->len);
 			read_idx++;
@@ -424,6 +432,30 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
 			u16 data_len;
 
 			skb = napi_build_skb((void *)resp_hw, PAGE_SIZE);
+			if (!skb) {
+				oq->stats->alloc_failures++;
+				read_idx++;
+				desc_used++;
+				if (read_idx == oq->max_count)
+					read_idx = 0;
+				data_len = buff_info->len - oq->max_single_buffer_size;
+				while (data_len) {
+					dma_unmap_page(oq->dev, oq->desc_ring[read_idx].buffer_ptr,
+							PAGE_SIZE, DMA_FROM_DEVICE);
+					buff_info = (struct octep_vf_rx_buffer *)&oq->buff_info[read_idx];
+					buff_info->page = NULL;
+					if (data_len < oq->buffer_size)
+						data_len = 0;
+					else
+						data_len -= oq->buffer_size;
+					read_idx++;
+					desc_used++;
+					if (read_idx == oq->max_count)
+						read_idx = 0;
+				}
+				continue;
+			}
+			rx_bytes += buff_info->len;
 			skb_reserve(skb, data_offset);
 			/* Head fragment includes response header(s);
 			 * subsequent fragments contains only data.
-- 
2.53.0