[PATCH 6.18 29/29] staging: rtl8723bs: fix out-of-bounds read in OnBeacon ESR IE parsing

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Navaneeth K <knavaneeth786@gmail.com>

commit 502ddcc405b69fa92e0add6c1714d654504f6fd7 upstream.

The Extended Supported Rates (ESR) IE handling in OnBeacon accessed
*(p + 1 + ielen) and *(p + 2 + ielen) without verifying that these
offsets lie within the received frame buffer. A malformed beacon with
an ESR IE positioned at the end of the buffer could cause an
out-of-bounds read, potentially triggering a kernel panic.

Add a boundary check to ensure that the ESR IE body and the subsequent
bytes are within the limits of the frame before attempting to access
them.

This prevents OOB reads caused by malformed beacon frames.

Signed-off-by: Navaneeth K <knavaneeth786@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/rtl8723bs/core/rtw_mlme_ext.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
@@ -588,9 +588,11 @@ unsigned int OnBeacon(struct adapter *pa
 
 	p = rtw_get_ie(pframe + sizeof(struct ieee80211_hdr_3addr) + _BEACON_IE_OFFSET_, WLAN_EID_EXT_SUPP_RATES, &ielen, precv_frame->u.hdr.len - sizeof(struct ieee80211_hdr_3addr) - _BEACON_IE_OFFSET_);
 	if (p && ielen > 0) {
-		if ((*(p + 1 + ielen) == 0x2D) && (*(p + 2 + ielen) != 0x2D))
-			/* Invalid value 0x2D is detected in Extended Supported Rates (ESR) IE. Try to fix the IE length to avoid failed Beacon parsing. */
-			*(p + 1) = ielen - 1;
+		if (p + 2 + ielen < pframe + len) {
+			if ((*(p + 1 + ielen) == 0x2D) && (*(p + 2 + ielen) != 0x2D))
+				/* Invalid value 0x2D is detected in Extended Supported Rates (ESR) IE. Try to fix the IE length to avoid failed Beacon parsing. */
+				*(p + 1) = ielen - 1;
+		}
 	}
 
 	if (pmlmeext->sitesurvey_res.state == SCAN_PROCESS) {