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 <adrien+dev@schischi.me>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Adrien Schildknecht 2015-07-28 10:30:16 +02:00 committed by Johannes Berg
parent 923b352f19
commit f5eeb5fa19

View File

@ -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)