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mac80211: warn when receiving frames with unaligned data

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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 <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Johannes Berg 2007-12-18 15:11:35 +01:00 committed by David S. Miller
parent 0d17440688
commit 81100eb80a
1 changed files with 13 additions and 0 deletions
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13
net/mac80211/rx.c
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@ -1443,6 +1443,7 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
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
@ -1472,6 +1473,18 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
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++;