netdev - Re: [PATCH v2] net: brcm80211: fix missing checks for kmemdup

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Date:   Fri, 15 Mar 2019 10:50:44 +0100
From:   Arend Van Spriel <arend.vanspriel@...adcom.com>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
        Wright Feng <wright.feng@...ress.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rafał Miłecki <rafal@...ecki.pl>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Chung-Hsien Hsu <stanley.hsu@...ress.com>,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        brcm80211-dev-list@...ress.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: brcm80211: fix missing checks for kmemdup

On 3/12/2019 5:39 AM, Kangjie Lu wrote:
> In case kmemdup fails, the fix sets conn_info->req_ie_len to zero
> to avoid buffer overflows.

Hi Kangjie,

See comment below. Also for v3 change prefix 'net:brcm80211:' to 
'brcmfmac:' instead.

> Signed-off-by: Kangjie Lu <kjlu@....edu>
> ---
>   drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index e92f6351bd22..5d9a3c35fef5 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -5464,6 +5464,8 @@ static s32 brcmf_get_assoc_ies(struct brcmf_cfg80211_info *cfg,
>   		conn_info->req_ie =
>   		    kmemdup(cfg->extra_buf, conn_info->req_ie_len,
>   			    GFP_KERNEL);
> +		if (!conn_info->req_ie)
> +			conn_info->req_ie_len = 0;

good.

>   	} else {
>   		conn_info->req_ie_len = 0;
>   		conn_info->req_ie = NULL;
> @@ -5480,6 +5482,8 @@ static s32 brcmf_get_assoc_ies(struct brcmf_cfg80211_info *cfg,
>   		conn_info->resp_ie =
>   		    kmemdup(cfg->extra_buf, conn_info->resp_ie_len,
>   			    GFP_KERNEL);
> +		if (!conn_info->resp_ie)
> +			conn_info->req_ie_len = 0;

bad! I think you took my comment too literal. Here it should set 
conn_info->resp_ie_len to zero.

Regards,
Arend

>   	} else {
>   		conn_info->resp_ie_len = 0;
>   		conn_info->resp_ie = NULL;
>