mwifiex: Fix possible buffer overflows in mwifiex_cmd_append_vsie_tlv()

mwifiex_cmd_append_vsie_tlv() calls memcpy() without checking
the destination size may trigger a buffer overflower,
which a local user could use to cause denial of service
or the execution of arbitrary code.
Fix it by putting the length check before calling memcpy().
Signed-off-by: Qing Xu <m1s5p6688@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/scan.c

@@ -2884,6 +2884,13 @@ mwifiex_cmd_append_vsie_tlv(struct mwifiex_private *priv,
 			vs_param_set->header.len =
 				cpu_to_le16((((u16) priv->vs_ie[id].ie[1])
 				& 0x00FF) + 2);
+			if (le16_to_cpu(vs_param_set->header.len) >
+				MWIFIEX_MAX_VSIE_LEN) {
+				mwifiex_dbg(priv->adapter, ERROR,
+					    "Invalid param length!\n");
+				break;
+			}
+
 			memcpy(vs_param_set->ie, priv->vs_ie[id].ie,
 			       le16_to_cpu(vs_param_set->header.len));
 			*buffer += le16_to_cpu(vs_param_set->header.len) +