Return-path: Received: from mail-wi0-f177.google.com ([209.85.212.177]:35665 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755362AbbG1Iax (ORCPT ); Tue, 28 Jul 2015 04:30:53 -0400 Received: by wibxm9 with SMTP id xm9so145925067wib.0 for ; Tue, 28 Jul 2015 01:30:51 -0700 (PDT) From: Adrien Schildknecht To: johannes@sipsolutions.net, davem@davemloft.net, thomas@net.t-labs.tu-berlin.de Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Adrien Schildknecht Subject: [PATCH] mac80211: fix invalid read in minstrel_sort_best_tp_rates() Date: Tue, 28 Jul 2015 10:30:16 +0200 Message-Id: <1438072216-19228-1-git-send-email-adrien+dev@schischi.me> (sfid-20150728_103201_012821_805C7127) Sender: linux-wireless-owner@vger.kernel.org List-ID: At the last iteration of the loop, j may equal zero and thus tp_list[j - 1] causes an invalid read. Changed the logic of the loop so that j - 1 is always >= 0. Signed-off-by: Adrien Schildknecht --- 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 247552a..3ece7d1 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) -- 2.4.6