linux-kernel - [PATCH AUTOSEL 4.14 04/21] mac80211: consider more elements in parsing CRC

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Message-Id: <20200223022411.2159-4-sashal@kernel.org>
Date:   Sat, 22 Feb 2020 21:23:54 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Johannes Berg <johannes.berg@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 04/21] mac80211: consider more elements in parsing CRC

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

[ Upstream commit a04564c99bb4a92f805a58e56b2d22cc4978f152 ]

We only use the parsing CRC for checking if a beacon changed,
and elements with an ID > 63 cannot be represented in the
filter. Thus, like we did before with WMM and Cisco vendor
elements, just statically add these forgotten items to the
CRC:
 - WLAN_EID_VHT_OPERATION
 - WLAN_EID_OPMODE_NOTIF

I guess that in most cases when VHT/HE operation change, the HT
operation also changed, and so the change was picked up, but we
did notice that pure operating mode notification changes were
ignored.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Luca Coelho <luciano.coelho@...el.com>
Link: https://lore.kernel.org/r/20200131111300.891737-22-luca@coelho.fi
[restrict to VHT for the mac80211 branch]
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/util.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 81f120466c38b..cd3cdd1a0b576 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -944,16 +944,22 @@ u32 ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 				elem_parse_failed = true;
 			break;
 		case WLAN_EID_VHT_OPERATION:
-			if (elen >= sizeof(struct ieee80211_vht_operation))
+			if (elen >= sizeof(struct ieee80211_vht_operation)) {
 				elems->vht_operation = (void *)pos;
-			else
-				elem_parse_failed = true;
+				if (calc_crc)
+					crc = crc32_be(crc, pos - 2, elen + 2);
+				break;
+			}
+			elem_parse_failed = true;
 			break;
 		case WLAN_EID_OPMODE_NOTIF:
-			if (elen > 0)
+			if (elen > 0) {
 				elems->opmode_notif = pos;
-			else
-				elem_parse_failed = true;
+				if (calc_crc)
+					crc = crc32_be(crc, pos - 2, elen + 2);
+				break;
+			}
+			elem_parse_failed = true;
 			break;
 		case WLAN_EID_MESH_ID:
 			elems->mesh_id = pos;
-- 
2.20.1