[PATCH] staging: rtl8723bs: fix OOB reads in rtw_get_wps_ie()

[Moksh Panicker]

rtw_get_wps_ie() iterates over IE data from network frames without
validating that the IE header and payload fit within the remaining
buffer before reading them. Specifically:

- in_ie[cnt + 1] is read without checking cnt + 1 < in_len
- memcmp(&in_ie[cnt + 2], ...) accesses cnt + 2 without bounds check
- in_ie[cnt + 1] is used as length without verifying payload fits

Add bounds checks at the top of the loop body to break early if fewer
than 2 bytes remain for the IE header, or if the declared payload
extends past the end of the buffer. Also require at least 4 bytes of
payload before comparing the WPS OUI.

Fixes: 554c0a3abf21 ("staging: rtl8723bs: add r8723bs driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Moksh Panicker <mokshpanicker.7@xxxxxxxxx>
---
 drivers/staging/rtl8723bs/core/rtw_ieee80211.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c b/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
index d0bbe1bb979c..82dc0ad27e79 100644
--- a/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
+++ b/drivers/staging/rtl8723bs/core/rtw_ieee80211.c
@@ -660,7 +660,14 @@ u8 *rtw_get_wps_ie(u8 *in_ie, uint in_len, u8 *wps_ie, uint *wps_ielen)
 	while (cnt < in_len) {
 		eid = in_ie[cnt];
 
-		if ((eid == WLAN_EID_VENDOR_SPECIFIC) && (!memcmp(&in_ie[cnt + 2], wps_oui, 4))) {
+		if (cnt + 2 > in_len)
+			break;
+
+		if (in_ie[cnt + 1] + 2 > in_len - cnt)
+			break;
+
+		if ((eid == WLAN_EID_VENDOR_SPECIFIC) && (in_ie[cnt + 1] >= 4) &&
+		    (!memcmp(&in_ie[cnt + 2], wps_oui, 4))) {
 			wpsie_ptr = &in_ie[cnt];
 
 			if (wps_ie)
-- 
2.34.1