Re: [PATCH ath-next 1/3] wifi: ath12k: validate RX frame length before undecapsulation

[Baochen Qiang <baochen.qiang@oss.qualcomm.com>]

On 10/16/2026 11:16 PM, Lorenzo Bianconi wrote:
> Reject truncated raw frames before removing the FCS trailer. Without this
> check, subtracting FCS_LEN from a shorter skb underflows and leaves the

skb_trim() has the check itself, so there will be no underflow?

> FCS untrimmed.
> 
> Also verify that the frame contains enough data for the 802.11 header and
> the crypto header before moving the header to make room for the crypto
> parameters.
> 
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
> 
> Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>
> ---
>  drivers/net/wireless/ath/ath12k/dp_rx.c       | 46 ++++++++++++++++++---------
>  drivers/net/wireless/ath/ath12k/dp_rx.h       | 10 +++---
>  drivers/net/wireless/ath/ath12k/wifi7/dp_rx.c | 22 +++++++++----
>  3 files changed, 51 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/dp_rx.c b/drivers/net/wireless/ath/ath12k/dp_rx.c
> index 36be543b7c50..40b8da34268f 100644
> --- a/drivers/net/wireless/ath/ath12k/dp_rx.c
> +++ b/drivers/net/wireless/ath/ath12k/dp_rx.c
> @@ -999,11 +999,11 @@ static void ath12k_dp_rx_h_undecap_nwifi(struct ath12k_pdev_dp *dp_pdev,
>  	memcpy(skb_push(msdu, hdr_len), decap_hdr, hdr_len);
>  }
>  
> -static void ath12k_dp_rx_h_undecap_raw(struct ath12k_pdev_dp *dp_pdev,
> -				       struct sk_buff *msdu,
> -				       enum hal_encrypt_type enctype,
> -				       struct ieee80211_rx_status *status,
> -				       bool decrypted)
> +static int ath12k_dp_rx_h_undecap_raw(struct ath12k_pdev_dp *dp_pdev,
> +				      struct sk_buff *msdu,
> +				      enum hal_encrypt_type enctype,
> +				      struct ieee80211_rx_status *status,
> +				      bool decrypted)
>  {
>  	struct ath12k_dp *dp = dp_pdev->dp;
>  	struct ath12k_skb_rxcb *rxcb = ATH12K_SKB_RXCB(msdu);
> @@ -1014,13 +1014,16 @@ static void ath12k_dp_rx_h_undecap_raw(struct ath12k_pdev_dp *dp_pdev,
>  	if (!rxcb->is_first_msdu ||
>  	    !(rxcb->is_first_msdu && rxcb->is_last_msdu)) {
>  		WARN_ON_ONCE(1);
> -		return;
> +		return 0;
>  	}
>  
> +	if (msdu->len < FCS_LEN)
> +		return -EINVAL;
> +

every later trim in this function has the same problem: msdu->len minus the MIC, ICV or
MMIC length is not checked either. should we add check for them as well?

>  	skb_trim(msdu, msdu->len - FCS_LEN);
>  
>  	if (!decrypted)
> -		return;
> +		return 0;
>  
>  	hdr = (void *)msdu->data;
>  

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