linux-hardening - Re: [PATCH 3/3] wifi: mwifiex: Sanity check tlv_len and tlv_bitmap

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Date:   Wed, 23 Aug 2023 15:38:57 -0700
From:   Justin Stitt <justinstitt@...gle.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     Brian Norris <briannorris@...omium.org>,
        Kalle Valo <kvalo@...nel.org>,
        Amitkumar Karwar <akarwar@...vell.com>,
        Xinming Hu <huxm@...vell.com>, Dan Williams <dcbw@...hat.com>,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 3/3] wifi: mwifiex: Sanity check tlv_len and tlv_bitmap_len

On Wed, Aug 23, 2023 at 3:33 PM Gustavo A. R. Silva
<gustavoars@...nel.org> wrote:
>
> Add sanity checks for both `tlv_len` and `tlv_bitmap_len` before
> decoding data from `event_buf`.
>
> This prevents any malicious or buggy firmware from overflowing
> `event_buf` through large values for `tlv_len` or `tlv_bitmap_len`.
>
> Suggested-by: Dan Williams <dcbw@...hat.com>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
Reviewed-by: Justin Stitt <justinstitt@...gle.com>

> ---
>  .../net/wireless/marvell/mwifiex/11n_rxreorder.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
> index 735aac52bdc4..9ee3b9f1e9ce 100644
> --- a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
> +++ b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
> @@ -921,6 +921,14 @@ void mwifiex_11n_rxba_sync_event(struct mwifiex_private *priv,
>         while (tlv_buf_left > sizeof(*tlv_rxba)) {
>                 tlv_type = le16_to_cpu(tlv_rxba->header.type);
>                 tlv_len  = le16_to_cpu(tlv_rxba->header.len);
> +               if (size_add(sizeof(tlv_rxba->header), tlv_len) > tlv_buf_left) {
> +                       mwifiex_dbg(priv->adapter, WARN,
> +                                   "TLV size (%ld) overflows event_buf (%d)\n",
> +                                   size_add(sizeof(tlv_rxba->header), tlv_len),
> +                                   tlv_buf_left);
> +                       return;
> +               }
> +
>                 if (tlv_type != TLV_TYPE_RXBA_SYNC) {
>                         mwifiex_dbg(priv->adapter, ERROR,
>                                     "Wrong TLV id=0x%x\n", tlv_type);
> @@ -929,6 +937,14 @@ void mwifiex_11n_rxba_sync_event(struct mwifiex_private *priv,
>
>                 tlv_seq_num = le16_to_cpu(tlv_rxba->seq_num);
>                 tlv_bitmap_len = le16_to_cpu(tlv_rxba->bitmap_len);
> +               if (size_add(sizeof(*tlv_rxba), tlv_bitmap_len) > tlv_buf_left) {
> +                       mwifiex_dbg(priv->adapter, WARN,
> +                                   "TLV size (%ld) overflows event_buf (%d)\n",
> +                                   size_add(sizeof(*tlv_rxba), tlv_bitmap_len),
> +                                   tlv_buf_left);
> +                       return;
> +               }
> +
>                 mwifiex_dbg(priv->adapter, INFO,
>                             "%pM tid=%d seq_num=%d bitmap_len=%d\n",
>                             tlv_rxba->mac, tlv_rxba->tid, tlv_seq_num,
> --
> 2.34.1
>