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PM / devfreq: Fix buffer overflow in trans_stat_show
Fix buffer overflow in trans_stat_show().
Convert simple snprintf to the more secure scnprintf with size of
PAGE_SIZE.
Add condition checking if we are exceeding PAGE_SIZE and exit early from
loop. Also add at the end a warning that we exceeded PAGE_SIZE and that
stats is disabled.
Return -EFBIG in the case where we don't have enough space to write the
full transition table.
Also document in the ABI that this function can return -EFBIG error.
Link: https://lore.kernel.org/all/20231024183016.14648-2-ansuelsmth@gmail.com/
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218041
Fixes: e552bbaf5b
("PM / devfreq: Add sysfs node for representing frequency transition information.")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
This commit is contained in:
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@ -52,6 +52,9 @@ Description:
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echo 0 > /sys/class/devfreq/.../trans_stat
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If the transition table is bigger than PAGE_SIZE, reading
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this will return an -EFBIG error.
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What: /sys/class/devfreq/.../available_frequencies
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Date: October 2012
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Contact: Nishanth Menon <nm@ti.com>
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@ -1688,7 +1688,7 @@ static ssize_t trans_stat_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct devfreq *df = to_devfreq(dev);
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ssize_t len;
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ssize_t len = 0;
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int i, j;
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unsigned int max_state;
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@ -1697,7 +1697,7 @@ static ssize_t trans_stat_show(struct device *dev,
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max_state = df->max_state;
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if (max_state == 0)
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return sprintf(buf, "Not Supported.\n");
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return scnprintf(buf, PAGE_SIZE, "Not Supported.\n");
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mutex_lock(&df->lock);
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if (!df->stop_polling &&
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@ -1707,31 +1707,52 @@ static ssize_t trans_stat_show(struct device *dev,
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}
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mutex_unlock(&df->lock);
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len = sprintf(buf, " From : To\n");
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len += sprintf(buf + len, " :");
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for (i = 0; i < max_state; i++)
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len += sprintf(buf + len, "%10lu",
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df->freq_table[i]);
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len += scnprintf(buf + len, PAGE_SIZE - len, " From : To\n");
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len += scnprintf(buf + len, PAGE_SIZE - len, " :");
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for (i = 0; i < max_state; i++) {
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if (len >= PAGE_SIZE - 1)
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break;
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len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu",
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df->freq_table[i]);
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}
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if (len >= PAGE_SIZE - 1)
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return PAGE_SIZE - 1;
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len += sprintf(buf + len, " time(ms)\n");
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len += scnprintf(buf + len, PAGE_SIZE - len, " time(ms)\n");
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for (i = 0; i < max_state; i++) {
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if (len >= PAGE_SIZE - 1)
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break;
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if (df->freq_table[i] == df->previous_freq)
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len += sprintf(buf + len, "*");
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len += scnprintf(buf + len, PAGE_SIZE - len, "*");
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else
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len += sprintf(buf + len, " ");
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len += scnprintf(buf + len, PAGE_SIZE - len, " ");
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if (len >= PAGE_SIZE - 1)
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break;
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len += sprintf(buf + len, "%10lu:", df->freq_table[i]);
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for (j = 0; j < max_state; j++)
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len += sprintf(buf + len, "%10u",
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df->stats.trans_table[(i * max_state) + j]);
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len += sprintf(buf + len, "%10llu\n", (u64)
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jiffies64_to_msecs(df->stats.time_in_state[i]));
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len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu:",
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df->freq_table[i]);
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for (j = 0; j < max_state; j++) {
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if (len >= PAGE_SIZE - 1)
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break;
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len += scnprintf(buf + len, PAGE_SIZE - len, "%10u",
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df->stats.trans_table[(i * max_state) + j]);
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}
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if (len >= PAGE_SIZE - 1)
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break;
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len += scnprintf(buf + len, PAGE_SIZE - len, "%10llu\n", (u64)
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jiffies64_to_msecs(df->stats.time_in_state[i]));
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}
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if (len < PAGE_SIZE - 1)
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len += scnprintf(buf + len, PAGE_SIZE - len, "Total transition : %u\n",
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df->stats.total_trans);
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if (len >= PAGE_SIZE - 1) {
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pr_warn_once("devfreq transition table exceeds PAGE_SIZE. Disabling\n");
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return -EFBIG;
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}
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len += sprintf(buf + len, "Total transition : %u\n",
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df->stats.total_trans);
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return len;
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}
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