[PATCH ath-next 1/2] wifi: ath11k: fix invalid data access in ath11k_dp_rx_h_undecap_nwifi

In certain cases, hardware might provide packets with a
length greater than the maximum native Wi-Fi header length.
This can lead to accessing and modifying fields in the header
within the ath11k_dp_rx_h_undecap_nwifi() function for the
DP_RX_DECAP_TYPE_NATIVE_WIFI decap type and
potentially result in invalid data access and memory corruption.

Kernel stack is corrupted in: ath11k_dp_rx_h_undecap+0x6b0/0x6b0 [ath11k]
Call trace:
 ath11k_dp_rx_h_mpdu+0x0/0x2e8 [ath11k]
 ath11k_dp_rx_h_mpdu+0x1e0/0x2e8 [ath11k]
 ath11k_dp_rx_wbm_err+0x1e0/0x450 [ath11k]
 ath11k_dp_rx_process_wbm_err+0x2fc/0x460 [ath11k]
 ath11k_dp_service_srng+0x2e0/0x348 [ath11k]

Add a sanity check before processing the SKB to prevent invalid
data access in the undecap native Wi-Fi function for the
DP_RX_DECAP_TYPE_NATIVE_WIFI decap type.

This adapted from the discussion/patch of the ath12k driver [1].

Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-04685-QCAHSPSWPL_V1_V2_SILICONZ_IOE-1

Link: https://lore.kernel.org/linux-wireless/[email protected]/ # [1]
Signed-off-by: Miaoqing Pan <[email protected]>
---
 drivers/net/wireless/ath/ath11k/dp_rx.c | 50 +++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/dp_rx.c b/drivers/net/wireless/ath/ath11k/dp_rx.c
index fe79109adc70..fbe2061a544d 100644
--- a/drivers/net/wireless/ath/ath11k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath11k/dp_rx.c
@@ -2502,6 +2502,29 @@ static void ath11k_dp_rx_deliver_msdu(struct ath11k *ar, struct napi_struct *nap
 	ieee80211_rx_napi(ar->hw, pubsta, msdu, napi);
 }
 
+static bool ath11k_dp_rx_check_nwifi_hdr_len_valid(struct ath11k_base *ab,
+						   struct hal_rx_desc *rx_desc,
+						   struct sk_buff *msdu)
+{
+	struct ieee80211_hdr *hdr;
+	u8 decap_type;
+	u32 hdr_len;
+
+	decap_type = ath11k_dp_rx_h_msdu_start_decap_type(ab, rx_desc);
+	if (decap_type != DP_RX_DECAP_TYPE_NATIVE_WIFI)
+		return true;
+
+	hdr = (struct ieee80211_hdr *)msdu->data;
+	hdr_len = ieee80211_hdrlen(hdr->frame_control);
+
+	if ((likely(hdr_len <= DP_MAX_NWIFI_HDR_LEN)))
+		return true;
+
+	ab->soc_stats.invalid_rbm++;
+	WARN_ON_ONCE(1);
+	return false;
+}
+
 static int ath11k_dp_rx_process_msdu(struct ath11k *ar,
 				     struct sk_buff *msdu,
 				     struct sk_buff_head *msdu_list,
@@ -2572,6 +2595,11 @@ static int ath11k_dp_rx_process_msdu(struct ath11k *ar,
 		}
 	}
 
+	if (unlikely(!ath11k_dp_rx_check_nwifi_hdr_len_valid(ab, rx_desc, msdu))) {
+		ret = -EINVAL;
+		goto free_out;
+	}
+
 	ath11k_dp_rx_h_ppdu(ar, rx_desc, rx_status);
 	ath11k_dp_rx_h_mpdu(ar, msdu, rx_desc, rx_status);
 
@@ -3261,6 +3289,12 @@ static int ath11k_dp_rx_h_verify_tkip_mic(struct ath11k *ar, struct ath11k_peer
 		    RX_FLAG_IV_STRIPPED | RX_FLAG_DECRYPTED;
 	skb_pull(msdu, hal_rx_desc_sz);
 
+	if (unlikely(!ath11k_dp_rx_check_nwifi_hdr_len_valid(ar->ab, rx_desc,
+							     msdu))) {
+		dev_kfree_skb_any(msdu);
+		return -EINVAL;
+	}
+
 	ath11k_dp_rx_h_ppdu(ar, rx_desc, rxs);
 	ath11k_dp_rx_h_undecap(ar, msdu, rx_desc,
 			       HAL_ENCRYPT_TYPE_TKIP_MIC, rxs, true);
@@ -3953,6 +3987,10 @@ static int ath11k_dp_rx_h_null_q_desc(struct ath11k *ar, struct sk_buff *msdu,
 		skb_put(msdu, hal_rx_desc_sz + l3pad_bytes + msdu_len);
 		skb_pull(msdu, hal_rx_desc_sz + l3pad_bytes);
 	}
+
+	if (unlikely(!ath11k_dp_rx_check_nwifi_hdr_len_valid(ar->ab, desc, msdu)))
+		return -EINVAL;
+
 	ath11k_dp_rx_h_ppdu(ar, desc, status);
 
 	ath11k_dp_rx_h_mpdu(ar, msdu, desc, status);
@@ -3997,7 +4035,7 @@ static bool ath11k_dp_rx_h_reo_err(struct ath11k *ar, struct sk_buff *msdu,
 	return drop;
 }
 
-static void ath11k_dp_rx_h_tkip_mic_err(struct ath11k *ar, struct sk_buff *msdu,
+static bool ath11k_dp_rx_h_tkip_mic_err(struct ath11k *ar, struct sk_buff *msdu,
 					struct ieee80211_rx_status *status)
 {
 	u16 msdu_len;
@@ -4005,6 +4043,7 @@ static void ath11k_dp_rx_h_tkip_mic_err(struct ath11k *ar, struct sk_buff *msdu,
 	u8 l3pad_bytes;
 	struct ath11k_skb_rxcb *rxcb = ATH11K_SKB_RXCB(msdu);
 	u32 hal_rx_desc_sz = ar->ab->hw_params.hal_desc_sz;
+	struct ath11k_base *ab = ar->ab;
 
 	rxcb->is_first_msdu = ath11k_dp_rx_h_msdu_end_first_msdu(ar->ab, desc);
 	rxcb->is_last_msdu = ath11k_dp_rx_h_msdu_end_last_msdu(ar->ab, desc);
@@ -4014,6 +4053,9 @@ static void ath11k_dp_rx_h_tkip_mic_err(struct ath11k *ar, struct sk_buff *msdu,
 	skb_put(msdu, hal_rx_desc_sz + l3pad_bytes + msdu_len);
 	skb_pull(msdu, hal_rx_desc_sz + l3pad_bytes);
 
+	if (unlikely(!ath11k_dp_rx_check_nwifi_hdr_len_valid(ab, desc, msdu)))
+		return true;
+
 	ath11k_dp_rx_h_ppdu(ar, desc, status);
 
 	status->flag |= (RX_FLAG_MMIC_STRIPPED | RX_FLAG_MMIC_ERROR |
@@ -4021,19 +4063,21 @@ static void ath11k_dp_rx_h_tkip_mic_err(struct ath11k *ar, struct sk_buff *msdu,
 
 	ath11k_dp_rx_h_undecap(ar, msdu, desc,
 			       HAL_ENCRYPT_TYPE_TKIP_MIC, status, false);
+
+	return false;
 }
 
 static bool ath11k_dp_rx_h_rxdma_err(struct ath11k *ar,  struct sk_buff *msdu,
 				     struct ieee80211_rx_status *status)
 {
 	struct ath11k_skb_rxcb *rxcb = ATH11K_SKB_RXCB(msdu);
-	bool drop = false;
+	bool drop;
 
 	ar->ab->soc_stats.rxdma_error[rxcb->err_code]++;
 
 	switch (rxcb->err_code) {
 	case HAL_REO_ENTR_RING_RXDMA_ECODE_TKIP_MIC_ERR:
-		ath11k_dp_rx_h_tkip_mic_err(ar, msdu, status);
+		drop = ath11k_dp_rx_h_tkip_mic_err(ar, msdu, status);
 		break;
 	default:
 		/* TODO: Review other rxdma error code to check if anything is
-- 
2.34.1