[PATCH] drivers/base/cpu: Use scnprintf() for avoiding potential buffer overflow

Takashi Iwai
2020-03-11T07:12:09Z

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit. Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
drivers/base/cpu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 6265871a4af2..0abcd9d68714 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -231,7 +231,7 @@ static struct cpu_attr cpu_attrs[] = {
static ssize_t print_cpus_kernel_max(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
+ int n = scnprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
return n;
}
static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
@@ -258,13 +258,13 @@ static ssize_t print_cpus_offline(struct device *dev,
buf[n++] = ',';

if (nr_cpu_ids == total_cpus-1)
- n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
+ n += scnprintf(&buf[n], len - n, "%u", nr_cpu_ids);
else
- n += snprintf(&buf[n], len - n, "%u-%d",
+ n += scnprintf(&buf[n], len - n, "%u-%d",
nr_cpu_ids, total_cpus-1);
}

- n += snprintf(&buf[n], len - n, "\n");
+ n += scnprintf(&buf[n], len - n, "\n");
return n;
}
static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
--
2.16.4