[PATCH 3.16 229/233] brcmfmac: fix possible buffer overflow in brcmf_cfg80211_mgmt_tx()

[Ben Hutchings]

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>

commit 8f44c9a41386729fea410e688959ddaa9d51be7c upstream.

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));

Fixes: 18e2f61db3b70 ("brcmfmac: P2P action frame tx.")
Reported-by: "freenerguo(éåå)" <freenerguo@xxxxxxxxxxx>
Signed-off-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
@@ -4119,6 +4119,11 @@ brcmf_cfg80211_mgmt_tx(struct wiphy *wip
 		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");