nl80211: correctly validate MU-MIMO groups

Since groups 0 and 63 are invalid, we should check for those bits.
Note that the 802.11 spec specifies the *bit* order, but the CPU
doesn't care about bit order since it can't address bits, so it's
always treating BIT(0) as the lowest bit within a byte.

Reported-by: Jan Fuchs <jan.fuchs@lancom.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -2764,8 +2764,8 @@ static int nl80211_parse_mon_options(struct cfg80211_registered_device *rdev,
 			nla_data(info->attrs[NL80211_ATTR_MU_MIMO_GROUP_DATA]);
 
 		/* bits 0 and 63 are reserved and must be zero */
-		if ((mumimo_groups[0] & BIT(7)) ||
-		    (mumimo_groups[VHT_MUMIMO_GROUPS_DATA_LEN - 1] & BIT(0)))
+		if ((mumimo_groups[0] & BIT(0)) ||
+		    (mumimo_groups[VHT_MUMIMO_GROUPS_DATA_LEN - 1] & BIT(7)))
 			return -EINVAL;
 
 		params->vht_mumimo_groups = mumimo_groups;