[PATCH] mac80211: warn when receiving frames with unaligned data
From: Johannes Berg <hidden>
Date: 2007-12-18 14:11:35
Also in:
linux-wireless
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 <redacted> --- 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++;