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

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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>
This commit is contained in:
Takashi Iwai 2020-03-11 08:08:51 +01:00 committed by Rafael J. Wysocki
parent 2c523b344d
commit 949fe25f2a
1 changed files with 10 additions and 10 deletions
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20
drivers/acpi/fan.c
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@ -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;
}