This is a note to let you know that I've just added the patch titled
PM / devfreq: Fix buffer overflow in trans_stat_show
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pm-devfreq-fix-buffer-overflow-in-trans_stat_show.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0ad57c14361cffe2434a4de131b2a24f0898300a
Author: Christian Marangi <ansuelsmth@xxxxxxxxx>
Date: Tue Oct 24 20:30:15 2023 +0200
PM / devfreq: Fix buffer overflow in trans_stat_show
[ Upstream commit 08e23d05fa6dc4fc13da0ccf09defdd4bbc92ff4 ]
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@xxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218041
Fixes: e552bbaf5b98 ("PM / devfreq: Add sysfs node for representing frequency transition information.")
Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index 5e6b74f30406..1e7e0bb4c14e 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -52,6 +52,9 @@ Description:
echo 0 > /sys/class/devfreq/.../trans_stat
+ If the transition table is bigger than PAGE_SIZE, reading
+ this will return an -EFBIG error.
+
What: /sys/class/devfreq/.../available_frequencies
Date: October 2012
Contact: Nishanth Menon <nm@xxxxxx>
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 14b83b8531d7..96dc49c207c7 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1656,7 +1656,7 @@ 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;
@@ -1665,7 +1665,7 @@ 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 &&
@@ -1675,31 +1675,52 @@ 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;
}
