From mboxrd@z Thu Jan 1 00:00:00 1970 From: Namhyung Kim Subject: [PATCH] compat: fix use of an uninitialized variable in compat_sys_io_setup() Date: Fri, 24 Dec 2010 18:16:26 +0900 Message-ID: <1293182186-23462-1-git-send-email-namhyung@gmail.com> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Moyer To: Alexander Viro Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:38640 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750775Ab0LXJR3 (ORCPT ); Fri, 24 Dec 2010 04:17:29 -0500 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: The upper bytes of ctx64 might contain garbages because it was set by get_user() which copied only lower 4 bytes as its second argument points to. Since sys_io_setup() requires its argumet is properly initialized to 0 we should set it explicitly. On x86, this was not a problem since its implementation of get_user() does a C assignment so that it can fill upper bytes with 0's. But other archs that use __get_user_asm() or something might have a problem. Signed-off-by: Namhyung Kim Cc: Jeff Moyer --- fs/compat.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/compat.c b/fs/compat.c index 4376e07febbb..b074e9f79148 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -526,7 +526,7 @@ asmlinkage long compat_sys_io_setup(unsigned nr_reqs, u32 __user *ctx32p) { long ret; - aio_context_t ctx64; + aio_context_t ctx64 = 0; mm_segment_t oldfs = get_fs(); if (unlikely(get_user(ctx64, ctx32p))) -- 1.7.3.4.600.g982838b0