[PATCH 5.18 0949/1095] tools/thermal: Fix possible path truncations

Greg Kroah-Hartman
2022-08-15T23:02:26Z

From: Florian Fainelli <f.fainelli@gmail.com>

[ Upstream commit 6c58cf40e3a1d2f47c09d3489857e9476316788a ]

A build with -D_FORTIFY_SOURCE=2 enabled will produce the following warnings:

sysfs.c:63:30: warning: '%s' directive output may be truncated writing up to 255 bytes into a region of size between 0 and 255 [-Wformat-truncation=]
snprintf(filepath, 256, "%s/%s", path, filename);
^~
Bump up the buffer to PATH_MAX which is the limit and account for all of
the possible NUL and separators that could lead to exceeding the
allocated buffer sizes.

Fixes: 94f69966faf8 ("tools/thermal: Introduce tmon, a tool for thermal subsystem")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/thermal/tmon/sysfs.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/tools/thermal/tmon/sysfs.c b/tools/thermal/tmon/sysfs.c
index b00b1bfd9d8e..cb1108bc9249 100644
--- a/tools/thermal/tmon/sysfs.c
+++ b/tools/thermal/tmon/sysfs.c
@@ -13,6 +13,7 @@
#include <stdint.h>
#include <dirent.h>
#include <libintl.h>
+#include <limits.h>
#include <ctype.h>
#include <time.h>
#include <syslog.h>
@@ -33,9 +34,9 @@ int sysfs_set_ulong(char *path, char *filename, unsigned long val)
{
FILE *fd;
int ret = -1;
- char filepath[256];
+ char filepath[PATH_MAX + 2]; /* NUL and '/' */

- snprintf(filepath, 256, "%s/%s", path, filename);
+ snprintf(filepath, sizeof(filepath), "%s/%s", path, filename);

fd = fopen(filepath, "w");
if (!fd) {
@@ -57,9 +58,9 @@ static int sysfs_get_ulong(char *path, char *filename, unsigned long *p_ulong)
{
FILE *fd;
int ret = -1;
- char filepath[256];
+ char filepath[PATH_MAX + 2]; /* NUL and '/' */

- snprintf(filepath, 256, "%s/%s", path, filename);
+ snprintf(filepath, sizeof(filepath), "%s/%s", path, filename);

fd = fopen(filepath, "r");
if (!fd) {
@@ -76,9 +77,9 @@ static int sysfs_get_string(char *path, char *filename, char *str)
{
FILE *fd;
int ret = -1;
- char filepath[256];
+ char filepath[PATH_MAX + 2]; /* NUL and '/' */

- snprintf(filepath, 256, "%s/%s", path, filename);
+ snprintf(filepath, sizeof(filepath), "%s/%s", path, filename);

fd = fopen(filepath, "r");
if (!fd) {
@@ -199,8 +200,8 @@ static int find_tzone_cdev(struct dirent *nl, char *tz_name,
{
unsigned long trip_instance = 0;
char cdev_name_linked[256];
- char cdev_name[256];
- char cdev_trip_name[256];
+ char cdev_name[PATH_MAX];
+ char cdev_trip_name[PATH_MAX];
int cdev_id;

if (nl->d_type == DT_LNK) {
@@ -213,7 +214,8 @@ static int find_tzone_cdev(struct dirent *nl, char *tz_name,
return -EINVAL;
}
/* find the link to real cooling device record binding */
- snprintf(cdev_name, 256, "%s/%s", tz_name, nl->d_name);
+ snprintf(cdev_name, sizeof(cdev_name) - 2, "%s/%s",
+ tz_name, nl->d_name);
memset(cdev_name_linked, 0, sizeof(cdev_name_linked));
if (readlink(cdev_name, cdev_name_linked,
sizeof(cdev_name_linked) - 1) != -1) {
@@ -226,8 +228,8 @@ static int find_tzone_cdev(struct dirent *nl, char *tz_name,
/* find the trip point in which the cdev is binded to
* in this tzone
*/
- snprintf(cdev_trip_name, 256, "%s%s", nl->d_name,
- "_trip_point");
+ snprintf(cdev_trip_name, sizeof(cdev_trip_name) - 1,
+ "%s%s", nl->d_name, "_trip_point");
sysfs_get_ulong(tz_name, cdev_trip_name,
&trip_instance);
/* validate trip point range, e.g. trip could return -1
--
2.35.1