ACK: [PATCH Zesty] brcmfmac: fix possible buffer overflow in brcmf_cfg80211_mgmt_tx()

[Colin Ian King]

On 22/08/17 10:08, Stefan Bader wrote:
> From: Arend van Spriel <arend.vanspriel at broadcom.com>
> 
> The lower level nl80211 code in cfg80211 ensures that "len" is between
> 25 and NL80211_ATTR_FRAME (2304).  We subtract DOT11_MGMT_HDR_LEN (24) from
> "len" so thats's max of 2280.  However, the action_frame->data[] buffer is
> only BRCMF_FIL_ACTION_FRAME_SIZE (1800) bytes long so this memcpy() can
> overflow.
> 
> 	memcpy(action_frame->data, &buf[DOT11_MGMT_HDR_LEN],
> 	       le16_to_cpu(action_frame->len));
> 
> Cc: stable at vger.kernel.org # 3.9.x
> Fixes: 18e2f61db3b70 ("brcmfmac: P2P action frame tx.")
> Reported-by: "freenerguo(郭大兴)" <freenerguo at tencent.com>
> Signed-off-by: Arend van Spriel <arend.vanspriel at broadcom.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> 
> CVE-2017-7541
> 
> (cherry-picked from commit 8f44c9a41386729fea410e688959ddaa9d51be7c)
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index dcde596..7e689c8 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -4934,6 +4934,11 @@ brcmf_cfg80211_mgmt_tx(struct wiphy *wiphy, struct wireless_dev *wdev,
>  		cfg80211_mgmt_tx_status(wdev, *cookie, buf, len, true,
>  					GFP_KERNEL);
>  	} else if (ieee80211_is_action(mgmt->frame_control)) {
> +		if (len > BRCMF_FIL_ACTION_FRAME_SIZE + DOT11_MGMT_HDR_LEN) {
> +			brcmf_err("invalid action frame length\n");
> +			err = -EINVAL;
> +			goto exit;
> +		}
>  		af_params = kzalloc(sizeof(*af_params), GFP_KERNEL);
>  		if (af_params == NULL) {
>  			brcmf_err("unable to allocate frame\n");
> 
Clean cherry pick.

Acked-by: Colin Ian King <colin.king at canonical.com>