From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 11 Mar 2020 07:08:51 +0000 (+0100)
Subject: ACPI: fan: Use scnprintf() for avoiding potential buffer overflow
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=949fe25f2ad31f72572dcad491843d355dc93b32;p=linux.git

ACPI: fan: Use scnprintf() for avoiding potential buffer overflow

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().

Also adjust the argument to really match with the actually remaining
buffer size.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
index aaf4e8f348cf3..873e039ad4b70 100644
--- a/drivers/acpi/fan.c
+++ b/drivers/acpi/fan.c
@@ -276,29 +276,29 @@ static ssize_t show_state(struct device *dev, struct device_attribute *attr, cha
 	int count;
 
 	if (fps->control == 0xFFFFFFFF || fps->control > 100)
-		count = snprintf(buf, PAGE_SIZE, "not-defined:");
+		count = scnprintf(buf, PAGE_SIZE, "not-defined:");
 	else
-		count = snprintf(buf, PAGE_SIZE, "%lld:", fps->control);
+		count = scnprintf(buf, PAGE_SIZE, "%lld:", fps->control);
 
 	if (fps->trip_point == 0xFFFFFFFF || fps->trip_point > 9)
-		count += snprintf(&buf[count], PAGE_SIZE, "not-defined:");
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "not-defined:");
 	else
-		count += snprintf(&buf[count], PAGE_SIZE, "%lld:", fps->trip_point);
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "%lld:", fps->trip_point);
 
 	if (fps->speed == 0xFFFFFFFF)
-		count += snprintf(&buf[count], PAGE_SIZE, "not-defined:");
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "not-defined:");
 	else
-		count += snprintf(&buf[count], PAGE_SIZE, "%lld:", fps->speed);
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "%lld:", fps->speed);
 
 	if (fps->noise_level == 0xFFFFFFFF)
-		count += snprintf(&buf[count], PAGE_SIZE, "not-defined:");
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "not-defined:");
 	else
-		count += snprintf(&buf[count], PAGE_SIZE, "%lld:", fps->noise_level * 100);
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "%lld:", fps->noise_level * 100);
 
 	if (fps->power == 0xFFFFFFFF)
-		count += snprintf(&buf[count], PAGE_SIZE, "not-defined\n");
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "not-defined\n");
 	else
-		count += snprintf(&buf[count], PAGE_SIZE, "%lld\n", fps->power);
+		count += scnprintf(&buf[count], PAGE_SIZE - count, "%lld\n", fps->power);
 
 	return count;
 }