[PATCH ath-next v3 1/4] wifi: ath12k: Handle error cases during extended skb allocation

[P Praneesh <praneesh.p@xxxxxxxxxxxxxxxx>]

Currently, in the case of extended skb allocation, the buffer is freed
before the DMA unmap operation. This premature deletion can result in
skb->data corruption, as the memory region could be re-allocated for other
purposes. Fix this issue by reordering the failure cases by calling
dma_unmap_single() first, then followed by the corresponding kfree_skb().
This helps avoid data corruption in case of failures in dp_tx().

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: P Praneesh <praneesh.p@xxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/ath/ath12k/dp_tx.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/dp_tx.c b/drivers/net/wireless/ath/ath12k/dp_tx.c
index 91da0805706f..9d58a9a9cbff 100644
--- a/drivers/net/wireless/ath/ath12k/dp_tx.c
+++ b/drivers/net/wireless/ath/ath12k/dp_tx.c
@@ -231,7 +231,7 @@ int ath12k_dp_tx(struct ath12k *ar, struct ath12k_link_vif *arvif,
 	struct ath12k_skb_cb *skb_cb = ATH12K_SKB_CB(skb);
 	struct hal_tcl_data_cmd *hal_tcl_desc;
 	struct hal_tx_msdu_ext_desc *msg;
-	struct sk_buff *skb_ext_desc;
+	struct sk_buff *skb_ext_desc = NULL;
 	struct hal_srng *tcl_ring;
 	struct ieee80211_hdr *hdr = (void *)skb->data;
 	struct ath12k_vif *ahvif = arvif->ahvif;
@@ -417,18 +417,15 @@ int ath12k_dp_tx(struct ath12k *ar, struct ath12k_link_vif *arvif,
 			if (ret < 0) {
 				ath12k_dbg(ab, ATH12K_DBG_DP_TX,
 					   "Failed to add HTT meta data, dropping packet\n");
-				kfree_skb(skb_ext_desc);
-				goto fail_unmap_dma;
+				goto fail_free_ext_skb;
 			}
 		}
 
 		ti.paddr = dma_map_single(ab->dev, skb_ext_desc->data,
 					  skb_ext_desc->len, DMA_TO_DEVICE);
 		ret = dma_mapping_error(ab->dev, ti.paddr);
-		if (ret) {
-			kfree_skb(skb_ext_desc);
-			goto fail_unmap_dma;
-		}
+		if (ret)
+			goto fail_free_ext_skb;
 
 		ti.data_len = skb_ext_desc->len;
 		ti.type = HAL_TCL_DESC_TYPE_EXT_DESC;
@@ -464,7 +461,7 @@ int ath12k_dp_tx(struct ath12k *ar, struct ath12k_link_vif *arvif,
 			ring_selector++;
 		}
 
-		goto fail_unmap_dma;
+		goto fail_unmap_dma_ext;
 	}
 
 	spin_lock_bh(&arvif->link_stats_lock);
@@ -491,13 +488,16 @@ int ath12k_dp_tx(struct ath12k *ar, struct ath12k_link_vif *arvif,
 
 	return 0;
 
-fail_unmap_dma:
-	dma_unmap_single(ab->dev, ti.paddr, ti.data_len, DMA_TO_DEVICE);
-
+fail_unmap_dma_ext:
 	if (skb_cb->paddr_ext_desc)
 		dma_unmap_single(ab->dev, skb_cb->paddr_ext_desc,
 				 sizeof(struct hal_tx_msdu_ext_desc),
 				 DMA_TO_DEVICE);
+fail_free_ext_skb:
+	kfree_skb(skb_ext_desc);
+
+fail_unmap_dma:
+	dma_unmap_single(ab->dev, ti.paddr, ti.data_len, DMA_TO_DEVICE);
 
 fail_remove_tx_buf:
 	ath12k_dp_tx_release_txbuf(dp, tx_desc, pool_id);
-- 
2.34.1