[PATCH net v2] gve: fix incorrect buffer cleanup in gve_tx_clean_pending_packets for QPL

[Joshua Washington <joshwash@google.com>]

From: Ankit Garg <nktgrg@google.com>

In DQ-QPL mode, gve_tx_clean_pending_packets() incorrectly uses the RDA
buffer cleanup path. It iterates num_bufs times and attempts to unmap
entries in the dma array.

This leads to two issues:
1. The dma array shares storage with tx_qpl_buf_ids (union).
 Interpreting buffer IDs as DMA addresses results in attempting to
 unmap incorrect memory locations.
2. num_bufs in QPL mode (counting 2K chunks) can significantly exceed
 the size of the dma array, causing out-of-bounds access warnings
(trace below is how we noticed this issue).

UBSAN: array-index-out-of-bounds in
drivers/net/ethernet/drivers/net/ethernet/google/gve/gve_tx_dqo.c:178:5 index 18 is out of
range for type 'dma_addr_t[18]' (aka 'unsigned long long[18]')
Workqueue: gve gve_service_task [gve]
Call Trace:
<TASK>
dump_stack_lvl+0x33/0xa0
__ubsan_handle_out_of_bounds+0xdc/0x110
gve_tx_stop_ring_dqo+0x182/0x200 [gve]
gve_close+0x1be/0x450 [gve]
gve_reset+0x99/0x120 [gve]
gve_service_task+0x61/0x100 [gve]
process_scheduled_works+0x1e9/0x380

Fix this by properly checking for QPL mode and delegating to
gve_free_tx_qpl_bufs() to reclaim the buffers.

Cc: stable@vger.kernel.org
Fixes: a6fb8d5a8b69 ("gve: Tx path for DQO-QPL")
Signed-off-by: Ankit Garg <nktgrg@google.com>
Reviewed-by: Jordan Rhee <jordanrhee@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
---
Changes in v2:
* Moved gve_unmap_packet up instead of forward declaration
  (Jakub Kicinski)
---
 drivers/net/ethernet/google/gve/gve_tx_dqo.c | 56 ++++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 31 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
index 40b89b3e..e5e33966 100644
--- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
@@ -167,6 +167,25 @@ gve_free_pending_packet(struct gve_tx_ring *tx,
 	}
 }
 
+static void gve_unmap_packet(struct device *dev,
+			     struct gve_tx_pending_packet_dqo *pkt)
+{
+	int i;
+
+	if (!pkt->num_bufs)
+		return;
+
+	/* SKB linear portion is guaranteed to be mapped */
+	dma_unmap_single(dev, dma_unmap_addr(pkt, dma[0]),
+			 dma_unmap_len(pkt, len[0]), DMA_TO_DEVICE);
+	for (i = 1; i < pkt->num_bufs; i++) {
+		netmem_dma_unmap_page_attrs(dev, dma_unmap_addr(pkt, dma[i]),
+					    dma_unmap_len(pkt, len[i]),
+					    DMA_TO_DEVICE, 0);
+	}
+	pkt->num_bufs = 0;
+}
+
 /* gve_tx_free_desc - Cleans up all pending tx requests and buffers.
  */
 static void gve_tx_clean_pending_packets(struct gve_tx_ring *tx)
@@ -176,21 +195,12 @@ static void gve_tx_clean_pending_packets(struct gve_tx_ring *tx)
 	for (i = 0; i < tx->dqo.num_pending_packets; i++) {
 		struct gve_tx_pending_packet_dqo *cur_state =
 			&tx->dqo.pending_packets[i];
-		int j;
-
-		for (j = 0; j < cur_state->num_bufs; j++) {
-			if (j == 0) {
-				dma_unmap_single(tx->dev,
-					dma_unmap_addr(cur_state, dma[j]),
-					dma_unmap_len(cur_state, len[j]),
-					DMA_TO_DEVICE);
-			} else {
-				dma_unmap_page(tx->dev,
-					dma_unmap_addr(cur_state, dma[j]),
-					dma_unmap_len(cur_state, len[j]),
-					DMA_TO_DEVICE);
-			}
-		}
+
+		if (tx->dqo.qpl)
+			gve_free_tx_qpl_bufs(tx, cur_state);
+		else
+			gve_unmap_packet(tx->dev, cur_state);
+
 		if (cur_state->skb) {
 			dev_consume_skb_any(cur_state->skb);
 			cur_state->skb = NULL;
@@ -1160,22 +1170,6 @@ static void remove_from_list(struct gve_tx_ring *tx,
 	}
 }
 
-static void gve_unmap_packet(struct device *dev,
-			     struct gve_tx_pending_packet_dqo *pkt)
-{
-	int i;
-
-	/* SKB linear portion is guaranteed to be mapped */
-	dma_unmap_single(dev, dma_unmap_addr(pkt, dma[0]),
-			 dma_unmap_len(pkt, len[0]), DMA_TO_DEVICE);
-	for (i = 1; i < pkt->num_bufs; i++) {
-		netmem_dma_unmap_page_attrs(dev, dma_unmap_addr(pkt, dma[i]),
-					    dma_unmap_len(pkt, len[i]),
-					    DMA_TO_DEVICE, 0);
-	}
-	pkt->num_bufs = 0;
-}
-
 /* Completion types and expected behavior:
  * No Miss compl + Packet compl = Packet completed normally.
  * Miss compl + Re-inject compl = Packet completed normally.
-- 
2.53.0.335.g19a08e0c02-goog