From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752255AbbJQUUS (ORCPT ); Sat, 17 Oct 2015 16:20:18 -0400 Received: from mail-lf0-f47.google.com ([209.85.215.47]:34740 "EHLO mail-lf0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751037AbbJQUUQ (ORCPT ); Sat, 17 Oct 2015 16:20:16 -0400 From: Rasmus Villemoes To: Andrew Morton , Alexei Starovoitov , "David S. Miller" Cc: Rasmus Villemoes , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe Date: Sat, 17 Oct 2015 22:20:05 +0200 Message-Id: <1445113206-27980-1-git-send-email-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.6.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As far as I can tell, strncpy_from_unsafe never returns -EFAULT. ret is the result of a __copy_from_user_inatomic(), which is 0 for success and positive (in this case necessarily 1) for access error - it is never negative. So we were always returning the length of the, possibly truncated, destination string. Signed-off-by: Rasmus Villemoes --- Probably not -stable-worthy. I can only find two callers, one of which ignores the return value. mm/maccess.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/maccess.c b/mm/maccess.c index 34fe24759ed1..d318db246826 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -99,5 +99,5 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count) pagefault_enable(); set_fs(old_fs); - return ret < 0 ? ret : src - unsafe_addr; + return ret ? -EFAULT : src - unsafe_addr; } -- 2.6.1