From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasiliy Kulikov Subject: [PATCH v2] fs: select: fix information leak to userspace Date: Sun, 14 Nov 2010 12:25:33 +0300 Message-ID: <20101114092533.GB5323@albatros> References: <1289421483-23907-1-git-send-email-segooon@gmail.com> <20101112120834.33062900.akpm@linux-foundation.org> <8D90F8B2-EA29-4EB9-9807-294CE0D5523B@dilger.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , kernel-janitors@vger.kernel.org, Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Andreas Dilger Return-path: Received: from mail-ew0-f46.google.com ([209.85.215.46]:33302 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754179Ab0KNJZj (ORCPT ); Sun, 14 Nov 2010 04:25:39 -0500 Content-Disposition: inline In-Reply-To: <8D90F8B2-EA29-4EB9-9807-294CE0D5523B@dilger.ca> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On some architectures __kernel_suseconds_t is int. On these archs struct timeval has padding bytes at the end. This struct is copied to userspace with these padding bytes uninitialized. This leads to leaking of contents of kernel stack memory. Signed-off-by: Vasiliy Kulikov --- Patch v1 used memset(), it was waste of cycles on almost all archs. Compile tested. fs/select.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/select.c b/fs/select.c index b7b10aa..43d4805 100644 --- a/fs/select.c +++ b/fs/select.c @@ -288,7 +288,6 @@ static int poll_select_copy_remaining(struct timespec *end_time, void __user *p, int timeval, int ret) { struct timespec rts; - struct timeval rtv; if (!p) return ret; @@ -306,8 +305,10 @@ static int poll_select_copy_remaining(struct timespec *end_time, void __user *p, rts.tv_sec = rts.tv_nsec = 0; if (timeval) { - rtv.tv_sec = rts.tv_sec; - rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC; + struct timeval rtv = { + .tv_sec = rts.tv_sec, + .tv_usec = rts.tv_nsec / NSEC_PER_USEC + }; if (!copy_to_user(p, &rtv, sizeof(rtv))) return ret; -- 1.7.0.4