From 280ba51d60be6f4ca3347eaa60783314f38df72e Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Tue, 18 Nov 2014 22:35:31 +0100 Subject: mac80211: minstrel_ht: fix a crash in rate sorting The commit 5935839ad73583781b8bbe8d91412f6826e218a4 "mac80211: improve minstrel_ht rate sorting by throughput & probability" introduced a crash on rate sorting that occurs when the rate added to the sorting array is faster than all the previous rates. Due to an off-by-one error, it reads the rate index from tp_list[-1], which contains uninitialized stack garbage, and then uses the resulting index for accessing the group rate stats, leading to a crash if the garbage value is big enough. Cc: Thomas Huehn Reported-by: Jouni Malinen Signed-off-by: Felix Fietkau Signed-off-by: Johannes Berg --- net/mac80211/rc80211_minstrel_ht.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) (limited to 'net/mac80211') diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c index df90ce2db00c..408fd8ab4eef 100644 --- a/net/mac80211/rc80211_minstrel_ht.c +++ b/net/mac80211/rc80211_minstrel_ht.c @@ -252,19 +252,16 @@ minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u8 index, cur_thr = mi->groups[cur_group].rates[cur_idx].cur_tp; cur_prob = mi->groups[cur_group].rates[cur_idx].probability; - tmp_group = tp_list[j - 1] / MCS_GROUP_RATES; - tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES; - tmp_thr = mi->groups[tmp_group].rates[tmp_idx].cur_tp; - tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability; - - while (j > 0 && (cur_thr > tmp_thr || - (cur_thr == tmp_thr && cur_prob > tmp_prob))) { - j--; + do { tmp_group = tp_list[j - 1] / MCS_GROUP_RATES; tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES; tmp_thr = mi->groups[tmp_group].rates[tmp_idx].cur_tp; tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability; - } + if (cur_thr < tmp_thr || + (cur_thr == tmp_thr && cur_prob <= tmp_prob)) + break; + j--; + } while (j > 0); if (j < MAX_THR_RATES - 1) { memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) * -- cgit v1.2.3