From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Berg Subject: [PATCH] mac80211: warn when receiving frames with unaligned data Date: Tue, 18 Dec 2007 15:11:35 +0100 Message-ID: <1197987095.4885.159.camel@johannes.berg> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: linux-wireless , netdev , Michael Wu , Herbert Xu , "David S. Miller" , Daniel Drake To: John Linville Return-path: Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org This patch makes mac80211 warn (once) when the driver passes up a frame in which the payload data is not aligned on a four-byte boundary, with a long comment for people who run into the condition and need to know what to do. Signed-off-by: Johannes Berg --- net/mac80211/rx.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- everything.orig/net/mac80211/rx.c 2007-12-18 14:47:18.433014323 +0100 +++ everything/net/mac80211/rx.c 2007-12-18 14:48:47.113014051 +0100 @@ -1619,6 +1619,7 @@ void __ieee80211_rx(struct ieee80211_hw struct ieee80211_sub_if_data *prev = NULL; struct sk_buff *skb_new; u8 *bssid; + int hdrlen; /* * key references and virtual interfaces are protected using RCU @@ -1648,6 +1649,18 @@ void __ieee80211_rx(struct ieee80211_hw rx.fc = le16_to_cpu(hdr->frame_control); type = rx.fc & IEEE80211_FCTL_FTYPE; + /* + * Drivers are required to align the payload data to a four-byte + * boundary, so the last two bits of the address where it starts + * may not be set. The header is required to be directly before + * the payload data, padding like atheros hardware adds which is + * inbetween the 802.11 header and the payload is not supported, + * the driver is required to move the 802.11 header further back + * in that case. + */ + hdrlen = ieee80211_get_hdrlen(rx.fc); + WARN_ON_ONCE(((unsigned long)(skb->data + hdrlen)) & 3); + if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT) local->dot11ReceivedFragmentCount++;