ath11k: Drop MSDU with length error in DP rx path

There are MSDUs whose length are invalid. For example,
attackers may inject on purpose truncated A-MSDUs with
invalid MSDU length.

Such MSDUs are marked with an err bit set in rx attention
tlvs, so we can check and drop them.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1
Signed-off-by: Baochen Qiang <bqiang@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210913180246.193388-2-jouni@codeaurora.org

drivers/net/wireless/ath/ath11k/dp_rx.c

@@ -142,6 +142,18 @@ static u32 ath11k_dp_rx_h_attn_mpdu_err(struct rx_attention *attn)
 	return errmap;
 }
 
+static bool ath11k_dp_rx_h_attn_msdu_len_err(struct ath11k_base *ab,
+					     struct hal_rx_desc *desc)
+{
+	struct rx_attention *rx_attention;
+	u32 errmap;
+
+	rx_attention = ath11k_dp_rx_get_attention(ab, desc);
+	errmap = ath11k_dp_rx_h_attn_mpdu_err(rx_attention);
+
+	return errmap & DP_RX_MPDU_ERR_MSDU_LEN;
+}
+
 static u16 ath11k_dp_rx_h_msdu_start_msdu_len(struct ath11k_base *ab,
 					      struct hal_rx_desc *desc)
 {
@@ -2525,6 +2537,12 @@ static int ath11k_dp_rx_process_msdu(struct ath11k *ar,
 	}
 
 	rx_desc = (struct hal_rx_desc *)msdu->data;
+	if (ath11k_dp_rx_h_attn_msdu_len_err(ab, rx_desc)) {
+		ath11k_warn(ar->ab, "msdu len not valid\n");
+		ret = -EIO;
+		goto free_out;
+	}
+
 	lrx_desc = (struct hal_rx_desc *)last_buf->data;
 	rx_attention = ath11k_dp_rx_get_attention(ab, lrx_desc);
 	if (!ath11k_dp_rx_h_attn_msdu_done(rx_attention)) {