The previous_freq value for a device could be an invalid frequency that
results in a error value being returned from devfreq_get_freq_level().
Check for an error value before using that to index into the transition
table.
Not doing this check will result in memory corruption when previous_freq is
not a valid frequency.
Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
---
drivers/devfreq/devfreq.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index a0b2f7e..f91ea29 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -101,14 +101,20 @@ static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
cur_time = jiffies;
devfreq->time_in_state[lev] +=
cur_time - devfreq->last_stat_updated;
- if (freq != devfreq->previous_freq) {
- prev_lev = devfreq_get_freq_level(devfreq,
- devfreq->previous_freq);
+ devfreq->last_stat_updated = cur_time;
+
+ if (freq == devfreq->previous_freq)
+ return 0;
+
+ prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
+ if (prev_lev < 0)
+ return 0;
+
+ if (lev != prev_lev) {
devfreq->trans_table[(prev_lev *
devfreq->profile->max_state) + lev]++;
devfreq->total_trans++;
}
- devfreq->last_stat_updated = cur_time;
return 0;
}
--
1.8.2.1
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