mwifiex: Fix possible buffer overflows at parsing bss descriptor

commit 13ec7f10b87f5fc04c4ccbd491c94c7980236a74 upstream.

mwifiex_update_bss_desc_with_ie() calls memcpy() unconditionally in
a couple places without checking the destination size.  Since the
source is given from user-space, this may trigger a heap buffer
overflow.

Fix it by putting the length check before performing memcpy().

This fix addresses CVE-2019-3846.

Reported-by: huangwen <huangwen@venustech.com.cn>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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/mwifiex/scan.c b/drivers/net/wireless/mwifiex/scan.c
index 45c5b3450cf5c719886483c9e0853c327fd62811..909dd6323edcb5f9067e1cbeaa40ecce91ab92e4 100644 (file)
--- a/drivers/net/wireless/mwifiex/scan.c
+++ b/drivers/net/wireless/mwifiex/scan.c
@@ -1171,6 +1171,8 @@ int mwifiex_update_bss_desc_with_ie(struct mwifiex_adapter *adapter,
                }
                switch (element_id) {
                case WLAN_EID_SSID:
+                       if (element_len > IEEE80211_MAX_SSID_LEN)
+                               return -EINVAL;
                        bss_entry->ssid.ssid_len = element_len;
                        memcpy(bss_entry->ssid.ssid, (current_ptr + 2),
                               element_len);
@@ -1180,6 +1182,8 @@ int mwifiex_update_bss_desc_with_ie(struct mwifiex_adapter *adapter,
                        break;
 
                case WLAN_EID_SUPP_RATES:
+                       if (element_len > MWIFIEX_SUPPORTED_RATES)
+                               return -EINVAL;
                        memcpy(bss_entry->data_rates, current_ptr + 2,
                               element_len);
                        memcpy(bss_entry->supported_rates, current_ptr + 2,