thinkpad_acpi: buffer overflow in fan_get_status()

The acpi_evalf() function modifies four bytes of data but in
fan_get_status() we pass a pointer to u8.  I have modified the
function to use type checking now.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 80e377949314..52daaa816e53 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -545,7 +545,7 @@ TPACPI_HANDLE(hkey, ec, "\\_SB.HKEY",	/* 600e/x, 770e, 770x */
  */
 
 static int acpi_evalf(acpi_handle handle,
-                      void *res, char *method, char *fmt, ...)
+                      int *res, char *method, char *fmt, ...)
 {
         char *fmt0 = fmt;
         struct acpi_object_list params;
@@ -606,7 +606,7 @@ static int acpi_evalf(acpi_handle handle,
                 success = (status == AE_OK &&
                            out_obj.type == ACPI_TYPE_INTEGER);
                 if (success && res)
-                        *(int *)res = out_obj.integer.value;
+                        *res = out_obj.integer.value;
                 break;
         case 'v':               /* void */
                 success = status == AE_OK;
@@ -7386,17 +7386,18 @@ static int fan_get_status(u8 *status)
          * Add TPACPI_FAN_RD_ACPI_FANS ? */
 
         switch (fan_status_access_mode) {
-        case TPACPI_FAN_RD_ACPI_GFAN:
+        case TPACPI_FAN_RD_ACPI_GFAN: {
                 /* 570, 600e/x, 770e, 770x */
+                int res;
 
-                if (unlikely(!acpi_evalf(gfan_handle, &s, NULL, "d")))
+                if (unlikely(!acpi_evalf(gfan_handle, &res, NULL, "d")))
                         return -EIO;
 
                 if (likely(status))
-                        *status = s & 0x07;
+                        *status = res & 0x07;
 
                 break;
-
+        }
         case TPACPI_FAN_RD_TPEC:
                 /* all except 570, 600e/x, 770e, 770x */
                 if (unlikely(!acpi_ec_read(fan_status_offset, &s)))