mwifiex: fix 802.11n/WPA detection

BugLink: https://bugs.launchpad.net/bugs/1845038

commit df612421 upstream.

Commit 63d7ef36 ("mwifiex: Don't abort on small, spec-compliant
vendor IEs") adjusted the ieee_types_vendor_header struct, which
inadvertently messed up the offsets used in
mwifiex_is_wpa_oui_present(). Add that offset back in, mirroring
mwifiex_is_rsn_oui_present().

As it stands, commit 63d7ef36 breaks compatibility with WPA (not
WPA2) 802.11n networks, since we hit the "info: Disable 11n if AES is
not supported by AP" case in mwifiex_is_network_compatible().

Fixes: 63d7ef36 ("mwifiex: Don't abort on small, spec-compliant vendor IEs")
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/net/wireless/mwifiex/main.h

@@ -108,6 +108,7 @@ enum {
 
 #define MWIFIEX_MAX_TOTAL_SCAN_TIME	(MWIFIEX_TIMER_10S - MWIFIEX_TIMER_1S)
 
+#define WPA_GTK_OUI_OFFSET				2
 #define RSN_GTK_OUI_OFFSET				2
 
 #define MWIFIEX_OUI_NOT_PRESENT			0

drivers/net/wireless/mwifiex/scan.c

@@ -151,7 +151,8 @@ mwifiex_is_wpa_oui_present(struct mwifiex_bssdescriptor *bss_desc, u32 cipher)
 	if (((bss_desc->bcn_wpa_ie) &&
 	     ((*(bss_desc->bcn_wpa_ie)).vend_hdr.element_id ==
 	      WLAN_EID_VENDOR_SPECIFIC))) {
-		iebody = (struct ie_body *) bss_desc->bcn_wpa_ie->data;
+		iebody = (struct ie_body *)((u8 *)bss_desc->bcn_wpa_ie->data +
+					    WPA_GTK_OUI_OFFSET);
 		oui = &mwifiex_wpa_oui[cipher][0];
 		ret = mwifiex_search_oui_in_ie(iebody, oui);
 		if (ret)