rndis_wlan: integer overflows in rndis_wlan_do_link_up_work()

If "offset" is negative then we can get past this check:
	if (offset > CONTROL_BUFFER_SIZE)
Or if we pick a very high "req_ie_len" then we can get around the check:
	if (offset + req_ie_len > CONTROL_BUFFER_SIZE)

I made "resp_ie_len" and "req_ie_len" unsigned.  I don't know if it was
intentional that they were signed in the original.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/net/wireless/rndis_wlan.c b/drivers/net/wireless/rndis_wlan.c
index a330c69583d6..dde45effef14 100644
--- a/drivers/net/wireless/rndis_wlan.c
+++ b/drivers/net/wireless/rndis_wlan.c
@@ -2755,9 +2755,10 @@ static void rndis_wlan_do_link_up_work(struct usbnet *usbdev)
         struct rndis_wlan_private *priv = get_rndis_wlan_priv(usbdev);
         struct ndis_80211_assoc_info *info = NULL;
         u8 bssid[ETH_ALEN];
-        int resp_ie_len, req_ie_len;
+        unsigned int resp_ie_len, req_ie_len;
+        unsigned int offset;
         u8 *req_ie, *resp_ie;
-        int ret, offset;
+        int ret;
         bool roamed = false;
         bool match_bss;
 
@@ -2785,7 +2786,9 @@ static void rndis_wlan_do_link_up_work(struct usbnet *usbdev)
                 ret = get_association_info(usbdev, info, CONTROL_BUFFER_SIZE);
                 if (!ret) {
                         req_ie_len = le32_to_cpu(info->req_ie_length);
-                        if (req_ie_len > 0) {
+                        if (req_ie_len > CONTROL_BUFFER_SIZE)
+                                req_ie_len = CONTROL_BUFFER_SIZE;
+                        if (req_ie_len != 0) {
                                 offset = le32_to_cpu(info->offset_req_ies);
 
                                 if (offset > CONTROL_BUFFER_SIZE)
@@ -2799,7 +2802,9 @@ static void rndis_wlan_do_link_up_work(struct usbnet *usbdev)
                         }
 
                         resp_ie_len = le32_to_cpu(info->resp_ie_length);
-                        if (resp_ie_len > 0) {
+                        if (resp_ie_len > CONTROL_BUFFER_SIZE)
+                                resp_ie_len = CONTROL_BUFFER_SIZE;
+                        if (resp_ie_len != 0) {
                                 offset = le32_to_cpu(info->offset_resp_ies);
 
                                 if (offset > CONTROL_BUFFER_SIZE)