Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759222Ab1DNP4d (ORCPT ); Thu, 14 Apr 2011 11:56:33 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:61345 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758734Ab1DNP4b (ORCPT ); Thu, 14 Apr 2011 11:56:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer; b=TdVfmgaT5iOtaFG+9qLebnTGGy4wWQ+fN0DkpeMYdBZphItct+OvrnViV+nj2wG/5m oLF8RjD7O0shAp0vFa/NCQ1qlTz4aH2yqFmou1mSyEYGB5ac+Lrhaz44kB9ujc/hAX0O dyKzZ3wZdnbne9I2E6KXLgPERGlm8d7fsEP7U= From: Vasiliy Kulikov To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , devel@driverdev.osuosl.org Subject: [PATCH] char: istallion: fix arbitrary kernel memory reads/writes Date: Thu, 14 Apr 2011 19:56:25 +0400 Message-Id: <1302796585-29504-1-git-send-email-segoon@openwall.com> X-Mailer: git-send-email 1.7.0.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2017 Lines: 52 stli_brdstats is defined as global variable. After de-BKL-ization in the patch b4eda9cb48eac1b7 an access to the variable is not serialized anymore. This leads to the race window between the check and the use in stli_getbrdstats(): if (copy_from_user(&stli_brdstats, bp, sizeof(combrd_t))) return -EFAULT; if (stli_brdstats.brd >= STL_MAXBRDS) <<< return -ENODEV; brdp = stli_brds[stli_brdstats.brd]; <<< If one process calls COM_GETBRDSTATS ioctl() with sane .brd, second process calls COM_GETBRDSTATS ioctl() with invalid .brd, and the second process' copy_from_user() executes exactly between the check and stli_brds[] indexation of the first process, then the first process gets contents of memory at *stli_brds[stli_brdstats.brd] address. Also the resulting .nrpanels field may be too big, in this case stli_brdstats.panels array overflows. Signed-off-by: Vasiliy Kulikov --- drivers/staging/tty/istallion.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/staging/tty/istallion.c b/drivers/staging/tty/istallion.c index 0b26627..ca18cbf 100644 --- a/drivers/staging/tty/istallion.c +++ b/drivers/staging/tty/istallion.c @@ -186,7 +186,6 @@ static struct ktermios stli_deftermios = { * re-used for each stats call. */ static comstats_t stli_comstats; -static combrd_t stli_brdstats; static struct asystats stli_cdkstats; /*****************************************************************************/ @@ -4005,6 +4004,7 @@ static int stli_getbrdstats(combrd_t __user *bp) { struct stlibrd *brdp; unsigned int i; + combrd_t stli_brdstats; if (copy_from_user(&stli_brdstats, bp, sizeof(combrd_t))) return -EFAULT; -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/