From: Johannes Berg Date: Tue, 8 Nov 2011 11:28:33 +0000 (+0100) Subject: mac80211: fix NULL dereference in radiotap code X-Git-Tag: firefly_0821_release~3680^2~3852^2^2~50 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f8d1ccf15568268c76f913b45ecdd33134387f1a;p=firefly-linux-kernel-4.4.55.git 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 fc88518916793af8ad6a02e05ff254d95c36d875 Author: Johannes Berg 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: Xiaokang Qin Cc: stable@vger.kernel.org Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index b867bd55de7a..097b42d286e2 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -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 */