5.15-stable review patch. If anyone has any objections, please let me know.
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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 --- Documentation/ABI/testing/sysfs-class-devfreq | 3 + drivers/devfreq/devfreq.c | 59 +++++++++++++++++--------- 2 files changed, 43 insertions(+), 19 deletions(-)
--- 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@ti.com --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1653,7 +1653,7 @@ static ssize_t trans_stat_show(struct de 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;
@@ -1662,7 +1662,7 @@ static ssize_t trans_stat_show(struct de 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 && @@ -1672,33 +1672,54 @@ static ssize_t trans_stat_show(struct de } 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, " "); } - 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, "%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]); + } + 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, "%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); + + 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; }