linux-user: fix settime old value location

old_value is the 4th argument of timer_settime(), not the 2nd.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: NPranith Kumar <bobby.prani@gmail.com>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Message-Id: <20170119151533.29328-1-bobby.prani@gmail.com>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>

linux-user/syscall.c

@@ -12043,10 +12043,14 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
             timer_t htimer = g_posix_timers[timerid];
             struct itimerspec hspec_new = {{0},}, hspec_old = {{0},};
 
-            target_to_host_itimerspec(&hspec_new, arg3);
+            if (target_to_host_itimerspec(&hspec_new, arg3)) {
+                goto efault;
+            }
             ret = get_errno(
                           timer_settime(htimer, arg2, &hspec_new, &hspec_old));
-            host_to_target_itimerspec(arg2, &hspec_old);
+            if (arg4 && host_to_target_itimerspec(arg4, &hspec_old)) {
+                goto efault;
+            }
         }
         break;
     }