mwifiex: fix use-after-free in beacon_ie processing

beacon_ie buffer is allocated in mwifiex_fill_new_bss_desc()
and the buffer pointer is saved in bss_desc->beacon_buf.
beacon_ie is freed before the function returns. However,
bss_desc->beacon_buf is still being accessed afterwards.

Fix it by freeing beacon_ie (bss_desc->beacon_buf) in
caller's scope.

Reviewed-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 17 insertions, 5 deletions

diff --git a/drivers/net/wireless/mwifiex/scan.c b/drivers/net/wireless/mwifiex/scan.c
index e7f6deaf715e..37b24e830844 100644
--- a/drivers/net/wireless/mwifiex/scan.c
+++ b/drivers/net/wireless/mwifiex/scan.c
@@ -1533,10 +1533,18 @@ static int mwifiex_update_curr_bss_params(struct mwifiex_private *priv,
         /* Make a copy of current BSSID descriptor */
         memcpy(&priv->curr_bss_params.bss_descriptor, bss_desc,
                sizeof(priv->curr_bss_params.bss_descriptor));
+
+        /* The contents of beacon_ie will be copied to its own buffer
+         * in mwifiex_save_curr_bcn()
+         */
         mwifiex_save_curr_bcn(priv);
         spin_unlock_irqrestore(&priv->curr_bcn_buf_lock, flags);
 
 done:
+        /* beacon_ie buffer was allocated in function
+         * mwifiex_fill_new_bss_desc(). Free it now.
+         */
+        kfree(bss_desc->beacon_buf);
         kfree(bss_desc);
         return 0;
 }
diff --git a/drivers/net/wireless/mwifiex/sta_ioctl.c b/drivers/net/wireless/mwifiex/sta_ioctl.c
index e6c9b2ae22ed..27729cfef151 100644
--- a/drivers/net/wireless/mwifiex/sta_ioctl.c
+++ b/drivers/net/wireless/mwifiex/sta_ioctl.c
@@ -140,12 +140,13 @@ int mwifiex_request_set_multicast_list(struct mwifiex_private *priv,
 /*
  * This function fills bss descriptor structure using provided
  * information.
+ * beacon_ie buffer is allocated in this function. It is caller's
+ * responsibility to free the memory.
  */
 int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
                               struct cfg80211_bss *bss,
                               struct mwifiex_bssdescriptor *bss_desc)
 {
-        int ret;
         u8 *beacon_ie;
         size_t beacon_ie_len;
         struct mwifiex_bss_priv *bss_priv = (void *)bss->priv;
@@ -165,6 +166,7 @@ int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
 
         memcpy(bss_desc->mac_address, bss->bssid, ETH_ALEN);
         bss_desc->rssi = bss->signal;
+        /* The caller of this function will free beacon_ie */
         bss_desc->beacon_buf = beacon_ie;
         bss_desc->beacon_buf_size = beacon_ie_len;
         bss_desc->beacon_period = bss->beacon_interval;
@@ -182,10 +184,7 @@ int mwifiex_fill_new_bss_desc(struct mwifiex_private *priv,
         else
                 bss_desc->bss_mode = NL80211_IFTYPE_STATION;
 
-        ret = mwifiex_update_bss_desc_with_ie(priv->adapter, bss_desc);
-
-        kfree(beacon_ie);
-        return ret;
+        return mwifiex_update_bss_desc_with_ie(priv->adapter, bss_desc);
 }
 
 static int mwifiex_process_country_ie(struct mwifiex_private *priv,
@@ -349,6 +348,11 @@ int mwifiex_bss_start(struct mwifiex_private *priv, struct cfg80211_bss *bss,
         }
 
 done:
+        /* beacon_ie buffer was allocated in function
+         * mwifiex_fill_new_bss_desc(). Free it now.
+         */
+        if (bss_desc)
+                kfree(bss_desc->beacon_buf);
         kfree(bss_desc);
         return ret;
 }