linux-kernel - Re: [PATCH v2] rtlwifi: Fix potential overflow on P2P code

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Date:   Sat, 19 Oct 2019 13:51:30 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Ping-Ke Shih <pkshih@...ltek.com>,
        "David S . Miller" <davem@...emloft.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Nicolas Waisman <nico@...mle.com>
Subject: Re: [PATCH v2] rtlwifi: Fix potential overflow on P2P code

Laura Abbott <labbott@...hat.com> writes:

> Nicolas Waisman noticed that even though noa_len is checked for
> a compatible length it's still possible to overrun the buffers
> of p2pinfo since there's no check on the upper bound of noa_num.
> Bound noa_num against P2P_MAX_NOA_NUM.
>
> Reported-by: Nicolas Waisman <nico@...mle.com>
> Signed-off-by: Laura Abbott <labbott@...hat.com>
> ---
> v2: Use P2P_MAX_NOA_NUM instead of erroring out.
> ---
>  drivers/net/wireless/realtek/rtlwifi/ps.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/wireless/realtek/rtlwifi/ps.c b/drivers/net/wireless/realtek/rtlwifi/ps.c
> index 70f04c2f5b17..fff8dda14023 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/ps.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/ps.c
> @@ -754,6 +754,9 @@ static void rtl_p2p_noa_ie(struct ieee80211_hw *hw, void *data,
>  				return;
>  			} else {
>  				noa_num = (noa_len - 2) / 13;
> +				if (noa_num > P2P_MAX_NOA_NUM)
> +					noa_num = P2P_MAX_NOA_NUM;
> +
>  			}
>  			noa_index = ie[3];
>  			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
> @@ -848,6 +851,9 @@ static void rtl_p2p_action_ie(struct ieee80211_hw *hw, void *data,
>  				return;
>  			} else {
>  				noa_num = (noa_len - 2) / 13;
> +				if (noa_num > P2P_MAX_NOA_NUM)
> +					noa_num = P2P_MAX_NOA_NUM;

IMHO using min() would be cleaner, but I'm fine with this as well. Up to
you.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches