[PATCH net v2 0/2] octeon_ep_vf: fix napi_build_skb() NULL dereference

[PATCH net v2 0/2] octeon_ep_vf: fix napi_build_skb() NULL dereference

[David Carlier]

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.

Patch 1 introduces a helper to deduplicate the ring index advance
pattern, patch 2 adds the actual NULL checks.

---
v1 -> v2: split into refactor + fix per Simon Horman review.
v1: https://lore.kernel.org/netdev/Z-6w5kfCJoGhb30g@framework/

David Carlier (2):
  octeon_ep_vf: introduce octep_vf_oq_next_idx() helper
  octeon_ep_vf: add NULL check for napi_build_skb()

 .../marvell/octeon_ep_vf/octep_vf_rx.c        | 47 ++++++++++++++-----
 1 file changed, 36 insertions(+), 11 deletions(-)

-- 
2.53.0

[PATCH net v2 1/2] octeon_ep_vf: introduce octep_vf_oq_next_idx() helper

[David Carlier]

Introduce octep_vf_oq_next_idx() to consolidate the repeated
ring index advance and wraparound pattern in __octep_vf_oq_process_rx().

No functional change intended.

Signed-off-by: David Carlier <devnexen@gmail.com>
---
 .../ethernet/marvell/octeon_ep_vf/octep_vf_rx.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

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..7bd1b9b8d7f5 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
@@ -352,6 +352,11 @@ static int octep_vf_oq_check_hw_for_pkts(struct octep_vf_device *oct,
 	return new_pkts;
 }
 
+static inline u32 octep_vf_oq_next_idx(struct octep_vf_oq *oq, u32 idx)
+{
+	return (idx + 1 == oq->max_count) ? 0 : idx + 1;
+}
+
 /**
  * __octep_vf_oq_process_rx() - Process hardware Rx queue and push to stack.
  *
@@ -415,10 +420,8 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
 			skb = napi_build_skb((void *)resp_hw, PAGE_SIZE);
 			skb_reserve(skb, data_offset);
 			skb_put(skb, buff_info->len);
-			read_idx++;
 			desc_used++;
-			if (read_idx == oq->max_count)
-				read_idx = 0;
+			read_idx = octep_vf_oq_next_idx(oq, read_idx);
 		} else {
 			struct skb_shared_info *shinfo;
 			u16 data_len;
@@ -429,10 +432,8 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
 			 * subsequent fragments contains only data.
 			 */
 			skb_put(skb, oq->max_single_buffer_size);
-			read_idx++;
 			desc_used++;
-			if (read_idx == oq->max_count)
-				read_idx = 0;
+			read_idx = octep_vf_oq_next_idx(oq, read_idx);
 
 			shinfo = skb_shinfo(skb);
 			data_len = buff_info->len - oq->max_single_buffer_size;
@@ -454,10 +455,8 @@ static int __octep_vf_oq_process_rx(struct octep_vf_device *oct,
 						buff_info->len,
 						buff_info->len);
 				buff_info->page = NULL;
-				read_idx++;
 				desc_used++;
-				if (read_idx == oq->max_count)
-					read_idx = 0;
+				read_idx = octep_vf_oq_next_idx(oq, read_idx);
 			}
 		}
 
-- 
2.53.0

[PATCH net v2 2/2] octeon_ep_vf: add NULL check for napi_build_skb()

[David Carlier]

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        | 30 +++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

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 7bd1b9b8d7f5..d98247408242 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
@@ -414,10 +414,15 @@ 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++;
+				desc_used++;
+				read_idx = octep_vf_oq_next_idx(oq, read_idx);
+				continue;
+			}
+			rx_bytes += buff_info->len;
 			skb_reserve(skb, data_offset);
 			skb_put(skb, buff_info->len);
 			desc_used++;
@@ -427,6 +432,27 @@ 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++;
+				desc_used++;
+				read_idx = octep_vf_oq_next_idx(oq, read_idx);
+				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;
+					desc_used++;
+					read_idx = octep_vf_oq_next_idx(oq, read_idx);
+				}
+				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