PM / devfreq: Fix buffer overflow in trans_stat_show

[linux-2.6-microblaze.git] / drivers / devfreq / devfreq.c

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index b3a68d5..907f50a 100644 (file)
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1688,7 +1688,7 @@ static ssize_t trans_stat_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
 {
        struct devfreq *df = to_devfreq(dev);
-       ssize_t len;
+       ssize_t len = 0;
        int i, j;
        unsigned int max_state;
 
@@ -1697,7 +1697,7 @@ static ssize_t trans_stat_show(struct device *dev,
        max_state = df->max_state;
 
        if (max_state == 0)
-               return sprintf(buf, "Not Supported.\n");
+               return scnprintf(buf, PAGE_SIZE, "Not Supported.\n");
 
        mutex_lock(&df->lock);
        if (!df->stop_polling &&
@@ -1707,31 +1707,52 @@ static ssize_t trans_stat_show(struct device *dev,
        }
        mutex_unlock(&df->lock);
 
-       len = sprintf(buf, "     From  :   To\n");
-       len += sprintf(buf + len, "           :");
-       for (i = 0; i < max_state; i++)
-               len += sprintf(buf + len, "%10lu",
-                               df->freq_table[i]);
+       len += scnprintf(buf + len, PAGE_SIZE - len, "     From  :   To\n");
+       len += scnprintf(buf + len, PAGE_SIZE - len, "           :");
+       for (i = 0; i < max_state; i++) {
+               if (len >= PAGE_SIZE - 1)
+                       break;
+               len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu",
+                                df->freq_table[i]);
+       }
+       if (len >= PAGE_SIZE - 1)
+               return PAGE_SIZE - 1;
 
-       len += sprintf(buf + len, "   time(ms)\n");
+       len += scnprintf(buf + len, PAGE_SIZE - len, "   time(ms)\n");
 
        for (i = 0; i < max_state; i++) {
+               if (len >= PAGE_SIZE - 1)
+                       break;
                if (df->freq_table[i] == df->previous_freq)
-                       len += sprintf(buf + len, "*");
+                       len += scnprintf(buf + len, PAGE_SIZE - len, "*");
                else
-                       len += sprintf(buf + len, " ");
+                       len += scnprintf(buf + len, PAGE_SIZE - len, " ");
+               if (len >= PAGE_SIZE - 1)
+                       break;
+
+               len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu:",
+                                df->freq_table[i]);
+               for (j = 0; j < max_state; j++) {
+                       if (len >= PAGE_SIZE - 1)
+                               break;
+                       len += scnprintf(buf + len, PAGE_SIZE - len, "%10u",
+                                        df->stats.trans_table[(i * max_state) + j]);
+               }
+               if (len >= PAGE_SIZE - 1)
+                       break;
+               len += scnprintf(buf + len, PAGE_SIZE - len, "%10llu\n", (u64)
+                                jiffies64_to_msecs(df->stats.time_in_state[i]));
+       }
 
-               len += sprintf(buf + len, "%10lu:", df->freq_table[i]);
-               for (j = 0; j < max_state; j++)
-                       len += sprintf(buf + len, "%10u",
-                               df->stats.trans_table[(i * max_state) + j]);
+       if (len < PAGE_SIZE - 1)
+               len += scnprintf(buf + len, PAGE_SIZE - len, "Total transition : %u\n",
+                                df->stats.total_trans);
 
-               len += sprintf(buf + len, "%10llu\n", (u64)
-                       jiffies64_to_msecs(df->stats.time_in_state[i]));
+       if (len >= PAGE_SIZE - 1) {
+               pr_warn_once("devfreq transition table exceeds PAGE_SIZE. Disabling\n");
+               return -EFBIG;
        }
 
-       len += sprintf(buf + len, "Total transition : %u\n",
-                                       df->stats.total_trans);
        return len;
 }