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

[PATCH] 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        | 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

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

[Simon Horman]

On Fri, Apr 03, 2026 at 09:07:32PM +0100, David Carlier wrote:
> 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>

Hi David,

I appreciate that this is on the fast path, and thus I expect it
is performance critical. But this patch largely duplicates code
already present in the same function. Would it be possible
refactor things a bit - e.g. using helpers - to make the change
a bit cleaner while not hurting performance?

If so, I'd suggest splitting patch(es) that refactor the code
from the patch that fixes the bug.

...

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

[David CARLIER]

Hi Simon,

On Wed, 8 Apr 2026 at 18:02, Simon Horman <horms@kernel.org> wrote:
>
> On Fri, Apr 03, 2026 at 09:07:32PM +0100, David Carlier wrote:
> > 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>
>
> Hi David,
>
> I appreciate that this is on the fast path, and thus I expect it
> is performance critical. But this patch largely duplicates code
> already present in the same function. Would it be possible
> refactor things a bit - e.g. using helpers - to make the change
> a bit cleaner while not hurting performance?
>
> If so, I'd suggest splitting patch(es) that refactor the code
> from the patch that fixes the bug.
>
> ...

Yes, valid points, I'll submit the v2 tomorrow. Cheers !