From: Johannes Berg <johannes.berg@intel.com>
Date: Thu, 8 Apr 2021 12:28:27 +0000 (+0200)
Subject: cfg80211: check S1G beacon compat element length
X-Git-Tag: v5.12-rc7~13^2~8^2~2
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b5ac0146492fc5c199de767e492be8a66471011a;p=linux-block.git

cfg80211: check S1G beacon compat element length

We need to check the length of this element so that we don't
access data beyond its end. Fix that.

Fixes: 9eaffe5078ca ("cfg80211: convert S1G beacon to scan results")
Link: https://lore.kernel.org/r/20210408142826.f6f4525012de.I9fdeff0afdc683a6024e5ea49d2daa3cd2459d11@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 019952d4fc7d..758eb7d2a706 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2352,14 +2352,16 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
 		return NULL;
 
 	if (ext) {
-		struct ieee80211_s1g_bcn_compat_ie *compat;
-		u8 *ie;
+		const struct ieee80211_s1g_bcn_compat_ie *compat;
+		const struct element *elem;
 
-		ie = (void *)cfg80211_find_ie(WLAN_EID_S1G_BCN_COMPAT,
-					      variable, ielen);
-		if (!ie)
+		elem = cfg80211_find_elem(WLAN_EID_S1G_BCN_COMPAT,
+					  variable, ielen);
+		if (!elem)
+			return NULL;
+		if (elem->datalen < sizeof(*compat))
 			return NULL;
-		compat = (void *)(ie + 2);
+		compat = (void *)elem->data;
 		bssid = ext->u.s1g_beacon.sa;
 		capability = le16_to_cpu(compat->compat_info);
 		beacon_int = le16_to_cpu(compat->beacon_int);