From 9f16b5c82a025cd4c864737409234ddc44fb166a Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Fri, 25 Nov 2022 12:36:57 +0100
Subject: [PATCH] wifi: cfg80211: fix buffer overflow in elem comparison
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Git-commit: 9f16b5c82a025cd4c864737409234ddc44fb166a
Patch-mainline: v6.1-rc8
References: git-fixes

For vendor elements, the code here assumes that 5 octets
are present without checking. Since the element itself is
already checked to fit, we only need to check the length.

Reported-and-tested-by: Sönke Huster <shuster@seemoo.tu-darmstadt.de>
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/wireless/scan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index da752b0cc752..4d217798890a 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -330,7 +330,8 @@ static size_t cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
 			 * determine if they are the same ie.
 			 */
 			if (tmp_old[0] == WLAN_EID_VENDOR_SPECIFIC) {
-				if (!memcmp(tmp_old + 2, tmp + 2, 5)) {
+				if (tmp_old[1] >= 5 && tmp[1] >= 5 &&
+				    !memcmp(tmp_old + 2, tmp + 2, 5)) {
 					/* same vendor ie, copy from
 					 * subelement
 					 */
-- 
2.35.3