From: Jan Kiszka <jan.kiszka@siemens.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Cc: Christian Marangi <ansuelsmth@gmail.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
Johnny Liu <johnliu@nvidia.com>,
Jon Hunter <jonathanh@nvidia.com>,
Linux PM list <linux-pm@vger.kernel.org>
Subject: [PATCH 5.10.y] PM / devfreq: Fix buffer overflow in trans_stat_show
Date: Sun, 28 Apr 2024 10:28:42 +0200 [thread overview]
Message-ID: <8a59f3b2-48b0-4a62-ab54-61f8d6068cbc@siemens.com> (raw)
From: Christian Marangi <ansuelsmth@gmail.com>
[ 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@gmail.com/
Cc: stable@vger.kernel.org
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@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
Original found by someone at Nvidia. But this backport is based on the
5.15 commit (796d3fad8c35ee9df9027899fb90ceaeb41b958f) where only a
conflict in sysfs-class-devfreq needed manual resolution.
Documentation/ABI/testing/sysfs-class-devfreq | 3 +
drivers/devfreq/devfreq.c | 59 +++++++++++++------
2 files changed, 43 insertions(+), 19 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index b8ebff4b1c4c..4514cf9fc7a1 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -66,6 +66,9 @@ 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/.../userspace/set_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 216594b86119..93df6cef4f5a 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1639,7 +1639,7 @@ 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;
@@ -1648,7 +1648,7 @@ static ssize_t trans_stat_show(struct device *dev,
max_state = df->profile->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 &&
@@ -1658,33 +1658,54 @@ 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->profile->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->profile->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->profile->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->profile->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]);
}
- len += sprintf(buf + len, "%10lu:",
- df->profile->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)
+ break;
+ len += scnprintf(buf + len, PAGE_SIZE - len, "%10llu\n", (u64)
+ jiffies64_to_msecs(df->stats.time_in_state[i]));
+ }
+
+ 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;
}
--
2.35.3
next reply other threads:[~2024-04-28 8:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-28 8:28 Jan Kiszka [this message]
2024-04-29 11:12 ` [PATCH 5.10.y] PM / devfreq: Fix buffer overflow in trans_stat_show Greg Kroah-Hartman
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