[PATCH 5.11 072/210] cfg80211: check S1G beacon compat element length

Greg Kroah-Hartman
2021-04-12T09:31:05Z

From: Johannes Berg <johannes.berg@intel.com>

commit b5ac0146492fc5c199de767e492be8a66471011a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/wireless/scan.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2352,14 +2352,16 @@ cfg80211_inform_single_bss_frame_data(st
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;
- compat = (void *)(ie + 2);
+ if (elem->datalen < sizeof(*compat))
+ return NULL;
+ 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);