1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c
index 6cf10cbc1eee..55c17afbe669 100644
--- a/drivers/acpi/fan.c
+++ b/drivers/acpi/fan.c
@@ -148,7 +148,7 @@ acpi_fan_write_state(struct file *file, const char __user * buffer,
         int result = 0;
         struct seq_file *m = file->private_data;
         struct acpi_device *device = m->private;
-        char state_string[12] = { '\0' };
+        char state_string[3] = { '\0' };
 
         if (count > sizeof(state_string) - 1)
                 return -EINVAL;
@@ -157,6 +157,12 @@ acpi_fan_write_state(struct file *file, const char __user * buffer,
                 return -EFAULT;
 
         state_string[count] = '\0';
+        if ((state_string[0] < '0') || (state_string[0] > '3'))
+                return -EINVAL;
+        if (state_string[1] == '\n')
+                state_string[1] = '\0';
+        if (state_string[1] != '\0')
+                return -EINVAL;
 
         result = acpi_bus_set_power(device->handle,
                                     simple_strtoul(state_string, NULL, 0));