[PATCH v2] wifi: ath11k: fix use after free in ath11k_dp_rx_msdu_coalesce.

[Willmar Knikker]

In ath11k_dp_rx_msdu_coalesce the loop uses ->is_continuation after
the dev_kfree_skb_any. This can cause a use after free kfence.

Use flag for caching is_continuation for use after the
dev_kfree_skb_any.

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Willmar Knikker <willmar at met-dubbel-l.nl>
Changes in v2:
 - add bool _is_continuation for use after the free.
 - Add Fixes, label to commit.
---
 drivers/net/wireless/ath/ath11k/dp_rx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index fe79109adc70..16364f76fc3c 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -1761,6 +1761,7 @@ static int ath11k_dp_rx_msdu_coalesce(struct ath11k *ar,
 	int buf_first_hdr_len, buf_first_len;
 	struct hal_rx_desc *ldesc;
 	int space_extra, rem_len, buf_len;
+	bool is_continuation;
 	u32 hal_rx_desc_sz = ar->ab->hw_params.hal_desc_sz;
 
 	/* As the msdu is spread across multiple rx buffers,
@@ -1810,7 +1811,8 @@ static int ath11k_dp_rx_msdu_coalesce(struct ath11k *ar,
 	rem_len = msdu_len - buf_first_len;
 	while ((skb = __skb_dequeue(msdu_list)) != NULL && rem_len > 0) {
 		rxcb = ATH11K_SKB_RXCB(skb);
-		if (rxcb->is_continuation)
+		is_continuation = rxcb->is_continuation;
+		if (is_continuation)
 			buf_len = DP_RX_BUFFER_SIZE - hal_rx_desc_sz;
 		else
 			buf_len = rem_len;
@@ -1828,7 +1830,7 @@ static int ath11k_dp_rx_msdu_coalesce(struct ath11k *ar,
 		dev_kfree_skb_any(skb);
 
 		rem_len -= buf_len;
-		if (!rxcb->is_continuation)
+		if (!is_continuation)
 			break;
 	}
 
-- 
2.54.0