This is a note to let you know that I've just added the patch titled
cpufreq: stats: Fix buffer overflow detection in trans_stats()
to the 6.6-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:
cpufreq-stats-fix-buffer-overflow-detection-in-trans_stats.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ea167a7fc2426f7685c3735e104921c1a20a6d3f Mon Sep 17 00:00:00 2001
From: Christian Marangi <ansuelsmth@xxxxxxxxx>
Date: Tue, 24 Oct 2023 20:30:14 +0200
Subject: cpufreq: stats: Fix buffer overflow detection in trans_stats()
From: Christian Marangi <ansuelsmth@xxxxxxxxx>
commit ea167a7fc2426f7685c3735e104921c1a20a6d3f upstream.
Commit 3c0897c180c6 ("cpufreq: Use scnprintf() for avoiding potential
buffer overflow") switched from snprintf to the more secure scnprintf
but never updated the exit condition for PAGE_SIZE.
As the commit say and as scnprintf document, what scnprintf returns what
is actually written not counting the '\0' end char. This results in the
case of len exceeding the size, len set to PAGE_SIZE - 1, as it can be
written at max PAGE_SIZE - 1 (as '\0' is not counted)
Because of len is never set to PAGE_SIZE, the function never break early,
never prints the warning and never return -EFBIG.
Fix this by changing the condition to PAGE_SIZE - 1 to correctly trigger
the error.
Cc: 5.10+ <stable@xxxxxxxxxxxxxxx> # 5.10+
Fixes: 3c0897c180c6 ("cpufreq: Use scnprintf() for avoiding potential buffer overflow")
Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/cpufreq_stats.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -131,23 +131,23 @@ static ssize_t show_trans_table(struct c
len += sysfs_emit_at(buf, len, " From : To\n");
len += sysfs_emit_at(buf, len, " : ");
for (i = 0; i < stats->state_num; i++) {
- if (len >= PAGE_SIZE)
+ if (len >= PAGE_SIZE - 1)
break;
len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);
}
- if (len >= PAGE_SIZE)
- return PAGE_SIZE;
+ if (len >= PAGE_SIZE - 1)
+ return PAGE_SIZE - 1;
len += sysfs_emit_at(buf, len, "\n");
for (i = 0; i < stats->state_num; i++) {
- if (len >= PAGE_SIZE)
+ if (len >= PAGE_SIZE - 1)
break;
len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);
for (j = 0; j < stats->state_num; j++) {
- if (len >= PAGE_SIZE)
+ if (len >= PAGE_SIZE - 1)
break;
if (pending)
@@ -157,12 +157,12 @@ static ssize_t show_trans_table(struct c
len += sysfs_emit_at(buf, len, "%9u ", count);
}
- if (len >= PAGE_SIZE)
+ if (len >= PAGE_SIZE - 1)
break;
len += sysfs_emit_at(buf, len, "\n");
}
- if (len >= PAGE_SIZE) {
+ if (len >= PAGE_SIZE - 1) {
pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
return -EFBIG;
}
Patches currently in stable-queue which might be from ansuelsmth@xxxxxxxxx are
queue-6.6/net-sfp-add-quirk-for-fiberstone-gpon-onu-34-20bi.patch
queue-6.6/cpufreq-stats-fix-buffer-overflow-detection-in-trans_stats.patch
