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Commit f8d1ccf1 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

mac80211: fix NULL dereference in radiotap code 



When receiving failed PLCP frames is enabled, there
won't be a rate pointer when we add the radiotap
header and thus the kernel will crash. Fix this by
not assuming the rate pointer is always valid. It's
still always valid for frames that have good PLCP
though, and that is checked & enforced.

This was broken by my
commit fc885189
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Fri Jul 30 13:23:12 2010 +0200

    mac80211: don't check rates on PLCP error frames

where I removed the check in this case but didn't
take into account that the rate info would be used.

Reported-by: default avatarXiaokang Qin <xiaokang.qin@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent cc438fcc

net/mac80211/rx.c

+6 −3
Original line number Diff line number Diff line
@@ -140,8 +140,9 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local, 
	pos++;



	/* IEEE80211_RADIOTAP_RATE */

	if (status->flag & RX_FLAG_HT) {

	if (!rate || status->flag & RX_FLAG_HT) {

		/*

		 * Without rate information don't add it. If we have,

		 * MCS information is a separate field in radiotap,

		 * added below. The byte here is needed as padding

		 * for the channel though, so initialise it to 0.
@@ -162,12 +163,14 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local, 
	else if (status->flag & RX_FLAG_HT)

		put_unaligned_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ,

				   pos);

	else if (rate->flags & IEEE80211_RATE_ERP_G)

	else if (rate && rate->flags & IEEE80211_RATE_ERP_G)

		put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,

				   pos);

	else

	else if (rate)

		put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ,

				   pos);

	else

		put_unaligned_le16(IEEE80211_CHAN_2GHZ, pos);

	pos += 2;



	/* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */