libertas: Fix two buffer overflows at parsing bss descriptor

commit e5e884b42639c74b5b57dc277909915c0aefc8bb upstream.

add_ie_rates() copys rates without checking the length
in bss descriptor from remote AP.when victim connects to
remote attacker, this may trigger buffer overflow.
lbs_ibss_join_existing() copys rates without checking the length
in bss descriptor from remote IBSS node.when victim connects to
remote attacker, this may trigger buffer overflow.
Fix them by putting the length check before performing copy.

This fix addresses CVE-2019-14896 and CVE-2019-14897.
This also fix build warning of mixed declarations and code.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Wen Huang <huangwenabc@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/wireless/libertas/cfg.c b/drivers/net/wireless/libertas/cfg.c
index 47a998d8f99e75bd5f59521a6593ca183cebb77a..ee5c9a3e1122f887b5551b710df611796d8abb04 100644 (file)
--- a/drivers/net/wireless/libertas/cfg.c
+++ b/drivers/net/wireless/libertas/cfg.c
@@ -272,6 +272,10 @@ add_ie_rates(u8 *tlv, const u8 *ie, int *nrates)
        int hw, ap, ap_max = ie[1];
        u8 hw_rate;
 
+       if (ap_max > MAX_RATES) {
+               lbs_deb_assoc("invalid rates\n");
+               return tlv;
+       }
        /* Advance past IE header */
        ie += 2;
 
@@ -1785,6 +1789,9 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
        struct cmd_ds_802_11_ad_hoc_join cmd;
        u8 preamble = RADIO_PREAMBLE_SHORT;
        int ret = 0;
+       int hw, i;
+       u8 rates_max;
+       u8 *rates;
 
        lbs_deb_enter(LBS_DEB_CFG80211);
 
@@ -1845,9 +1852,12 @@ static int lbs_ibss_join_existing(struct lbs_private *priv,
        if (!rates_eid) {
                lbs_add_rates(cmd.bss.rates);
        } else {
-               int hw, i;
-               u8 rates_max = rates_eid[1];
-               u8 *rates = cmd.bss.rates;
+               rates_max = rates_eid[1];
+               if (rates_max > MAX_RATES) {
+                       lbs_deb_join("invalid rates");
+                       goto out;
+               }
+               rates = cmd.bss.rates;
                for (hw = 0; hw < ARRAY_SIZE(lbs_rates); hw++) {
                        u8 hw_rate = lbs_rates[hw].bitrate / 5;
                        for (i = 0; i < rates_max; i++) {