build_skb() returns NULL in case of a memory allocation failure so handle
it inside __octep_oq_process_rx() to avoid NULL pointer dereference.
__octep_oq_process_rx() is called during NAPI polling by the driver. If
skb allocation fails, keep on pulling packets out of the Rx DMA queue: we
shouldn't break the polling immediately and thus falsely indicate to the
octep_napi_poll() that the Rx pressure is going down. As there is no
associated skb in this case, don't process the packets and don't push them
up the network stack - they are skipped.
Helper function is implemented to unmmap/flush all the fragment buffers
used by the dropped packet. 'alloc_failures' counter is incremented to
mark the skb allocation error in driver statistics.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 37d79d059606 ("octeon_ep: add Tx/Rx processing and interrupt support")
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
Compile tested only.
v4:
- Split patch up as suggested by Jakub
(https://lore.kernel.org/all/20241004073311.223efca4@kernel.org/)
v3: https://lore.kernel.org/all/20240930053328.9618-1-amishin@t-argos.ru/
- Optimize helper as suggested by Paolo
(https://lore.kernel.org/all/b9ae8575-f903-425f-aa42-0c2a7605aa94@redhat.com/)
- v3 has been reviewed-by Simon Horman
(https://lore.kernel.org/all/20240930162622.GF1310185@kernel.org/)
v2: https://lore.kernel.org/all/20240916060212.12393-1-amishin@t-argos.ru/
- Implement helper instead of adding multiple checks for '!skb' and
remove 'rx_bytes' increasing in case of packet dropping as suggested
by Paolo
(https://lore.kernel.org/all/ba514498-3706-413b-a09f-f577861eef28@redhat.com/)
v1: https://lore.kernel.org/all/20240906063907.9591-1-amishin@t-argos.ru/
.../net/ethernet/marvell/octeon_ep/octep_rx.c | 27 +++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/drivers/net/ethernet/marvell/octeon_ep/octep_rx.c b/drivers/net/ethernet/marvell/octeon_ep/octep_rx.c
index 62db101b2147..2d9d95071786 100644
--- a/drivers/net/ethernet/marvell/octeon_ep/octep_rx.c
+++ b/drivers/net/ethernet/marvell/octeon_ep/octep_rx.c
@@ -360,6 +360,27 @@ static void octep_oq_next_pkt(struct octep_oq *oq,
*read_idx = 0;
}
+/**
+ * octep_oq_drop_rx() - Free the resources associated with a packet.
+ *
+ * @oq: Octeon Rx queue data structure.
+ * @buff_info: Current packet buffer info.
+ * @read_idx: Current packet index in the ring.
+ * @desc_used: Current packet descriptor number.
+ *
+ */
+static void octep_oq_drop_rx(struct octep_oq *oq,
+ struct octep_rx_buffer *buff_info,
+ u32 *read_idx, u32 *desc_used)
+{
+ int data_len = buff_info->len - oq->max_single_buffer_size;
+
+ do {
+ octep_oq_next_pkt(oq, buff_info, read_idx, desc_used);
+ data_len -= oq->buffer_size;
+ } while (data_len > 0);
+}
+
/**
* __octep_oq_process_rx() - Process hardware Rx queue and push to stack.
*
@@ -417,6 +438,12 @@ static int __octep_oq_process_rx(struct octep_device *oct,
}
skb = build_skb((void *)resp_hw, PAGE_SIZE);
+ if (!skb) {
+ octep_oq_drop_rx(oq, buff_info,
+ &read_idx, &desc_used);
+ oq->stats.alloc_failures++;
+ continue;
+ }
skb_reserve(skb, data_offset);
octep_oq_next_pkt(oq, buff_info, &read_idx, &desc_used);
--
2.30.2