From f5eeb5fa191fd7b634cbc4883ac58f3b2184dbc5 Mon Sep 17 00:00:00 2001 From: Adrien Schildknecht Date: Tue, 28 Jul 2015 10:30:16 +0200 Subject: [PATCH] mac80211: fix invalid read in minstrel_sort_best_tp_rates() At the last iteration of the loop, j may equal zero and thus tp_list[j - 1] causes an invalid read. Change the logic of the loop so that j - 1 is always >= 0. Cc: stable@vger.kernel.org Signed-off-by: Adrien Schildknecht Signed-off-by: Johannes Berg --- net/mac80211/rc80211_minstrel.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c index 247552a7f6c2..3ece7d1034c8 100644 --- a/net/mac80211/rc80211_minstrel.c +++ b/net/mac80211/rc80211_minstrel.c @@ -92,14 +92,15 @@ int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma) static inline void minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list) { - int j = MAX_THR_RATES; - struct minstrel_rate_stats *tmp_mrs = &mi->r[j - 1].stats; + int j; + struct minstrel_rate_stats *tmp_mrs; struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats; - while (j > 0 && (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) > - minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))) { - j--; + for (j = MAX_THR_RATES; j > 0; --j) { tmp_mrs = &mi->r[tp_list[j - 1]].stats; + if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <= + minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma)) + break; } if (j < MAX_THR_RATES - 1)