linux-kernel - Re: [PATCH] staging: wfx: check ssidlen and prevent an array overflow

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Date:   Fri, 24 Apr 2020 11:39:38 +0000
From:   Jerome Pouiller <Jerome.Pouiller@...abs.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] staging: wfx: check ssidlen and prevent an array overflow

On Friday 24 April 2020 12:42:35 CEST Dan Carpenter wrote:
> 
> We need to cap "ssidlen" to prevent a memcpy() overflow.
> 
> Fixes: 40115bbc40e2 ("staging: wfx: implement the rest of mac80211 API")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
>  drivers/staging/wfx/sta.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c
> index c73dbb3a0de8c..3bff0f1e3d9ba 100644
> --- a/drivers/staging/wfx/sta.c
> +++ b/drivers/staging/wfx/sta.c
> @@ -479,7 +479,9 @@ static void wfx_do_join(struct wfx_vif *wvif)
>                 ssidie = ieee80211_bss_get_ie(bss, WLAN_EID_SSID);
>         if (ssidie) {
>                 ssidlen = ssidie[1];
> -               memcpy(ssid, &ssidie[2], ssidie[1]);
> +               if (ssidlen > IEEE80211_MAX_SSID_LEN)
> +                       ssidlen = IEEE80211_MAX_SSID_LEN;
I'd have a little preference for sizeof(ssid) instead of
IEEE80211_MAX_SSID_LEN, but ok.

> +               memcpy(ssid, &ssidie[2], ssidlen);
>         }
>         rcu_read_unlock();
> 
> --
> 2.26.1
> 

Reviewed-by: Jérôme Pouiller <jerome.pouiller@...abs.com>

-- 
Jérôme Pouiller