Subject: [PATCH AUTOSEL 4.20 223/304] mac80211: fix radiotap vendor presence bitmap handling

From: Sasha Levin <[email-masked]>
Date: Mon, 28 Jan 2019 10:42:20 -0500

From: Johannes Berg <[email-masked]>

[ Upstream commit efc38dd7d5fa5c8cdd0c917c5d00947aa0539443 ]

Due to the alignment handling, it actually matters where in the code
we add the 4 bytes for the presence bitmap to the length; the first
field is the timestamp with 8 byte alignment so we need to add the
space for the extra vendor namespace presence bitmap *before* we do
any alignment for the fields.

Move the presence bitmap length accounting to the right place to fix
the alignment for the data properly.

Signed-off-by: Johannes Berg <[email-masked]>
Signed-off-by: Luca Coelho <[email-masked]>
Signed-off-by: Johannes Berg <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 net/mac80211/rx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 77d996a60f12..85c365fc7a0c 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -143,6 +143,9 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
 	/* allocate extra bitmaps */
 	if (status->chains)
 		len += 4 * hweight8(status->chains);
+	/* vendor presence bitmap */
+	if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA)
+		len += 4;
 
 	if (ieee80211_have_rx_timestamp(status)) {
 		len = ALIGN(len, 8);
@@ -207,8 +210,6 @@ ieee80211_rx_radiotap_hdrlen(struct ieee80211_local *local,
 	if (status->flag & RX_FLAG_RADIOTAP_VENDOR_DATA) {
 		struct ieee80211_vendor_radiotap *rtap = (void *)skb->data;
 
-		/* vendor presence bitmap */
-		len += 4;
 		/* alignment for fixed 6-byte vendor data header */
 		len = ALIGN(len, 2);
 		/* vendor data header */
-- 
2.19.1