From bdc56dcb177cd4858e89fa1e2727e1f0cbe90aad Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Tue, 8 Nov 2011 12:28:33 +0100 Subject: [PATCH] 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 99631ba62d1da94e1dfd87963f5c87ffd7d0a3ca 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 --- net/mac80211/rx.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index b867bd55de7aa..097b42d286e24 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 */ -- 2.39.5