From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D65A8CA9EC9 for ; Mon, 4 Nov 2019 21:51:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1AFD21850 for ; Mon, 4 Nov 2019 21:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572904287; bh=x6vR3NQ+bGrQ/ymKfMGPZ1eXkd7tZ1So3e3ueerPjaU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=oEP/z7BpA0+bg9VGNCZfmz2F42a6uj6hggjUyOiiIxBFatcCKn7a2KqzxRL5+XeAj p1TdP4FhvsPYirYqa+3j2IW5lnAU5bnivMGq6SvUGxAWd162XdOLWYg9nNJn5/pXKa DrXGFXf59KwsLdHrmR4nLUbNZaOHFpGpd4O58SaA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730514AbfKDVv0 (ORCPT ); Mon, 4 Nov 2019 16:51:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:44296 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730057AbfKDVvU (ORCPT ); Mon, 4 Nov 2019 16:51:20 -0500 Received: from localhost (6.204-14-84.ripe.coltfrance.com [84.14.204.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BA01B21929; Mon, 4 Nov 2019 21:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572904279; bh=x6vR3NQ+bGrQ/ymKfMGPZ1eXkd7tZ1So3e3ueerPjaU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ELsVVh0c9XxX/1r8nNhq8UnNgzeMQ2aDRxoX4rnZF8hi68nR1zxl3M3PY/Ar5+R8H NnExMALBGo3vCz9X37N+G3NlsjbcHmzr/93ziKkQ2I2UDXaxRxgWlPcAFOjMqFlzbl SRUPSR5TjGGVAElz9wr5RtMgO8wF3MdF2JqeCj9w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yihui Zeng , Dan Carpenter , Heiko Carstens , Vasily Gorbik Subject: [PATCH 4.9 48/62] s390/cmm: fix information leak in cmm_timeout_handler() Date: Mon, 4 Nov 2019 22:45:10 +0100 Message-Id: <20191104211951.474918795@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191104211901.387893698@linuxfoundation.org> References: <20191104211901.387893698@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yihui ZENG commit b8e51a6a9db94bc1fb18ae831b3dab106b5a4b5f upstream. The problem is that we were putting the NUL terminator too far: buf[sizeof(buf) - 1] = '\0'; If the user input isn't NUL terminated and they haven't initialized the whole buffer then it leads to an info leak. The NUL terminator should be: buf[len - 1] = '\0'; Signed-off-by: Yihui Zeng Cc: stable@vger.kernel.org Signed-off-by: Dan Carpenter [heiko.carstens@de.ibm.com: keep semantics of how *lenp and *ppos are handled] Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/mm/cmm.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -306,16 +306,16 @@ static int cmm_timeout_handler(struct ct } if (write) { - len = *lenp; - if (copy_from_user(buf, buffer, - len > sizeof(buf) ? sizeof(buf) : len)) + len = min(*lenp, sizeof(buf)); + if (copy_from_user(buf, buffer, len)) return -EFAULT; - buf[sizeof(buf) - 1] = '\0'; + buf[len - 1] = '\0'; cmm_skip_blanks(buf, &p); nr = simple_strtoul(p, &p, 0); cmm_skip_blanks(p, &p); seconds = simple_strtoul(p, &p, 0); cmm_set_timeout(nr, seconds); + *ppos += *lenp; } else { len = sprintf(buf, "%ld %ld\n", cmm_timeout_pages, cmm_timeout_seconds); @@ -323,9 +323,9 @@ static int cmm_timeout_handler(struct ct len = *lenp; if (copy_to_user(buffer, buf, len)) return -EFAULT; + *lenp = len; + *ppos += len; } - *lenp = len; - *ppos += len; return 0; }