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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 17C73C4360F for ; Fri, 15 Feb 2019 02:24:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFC6420836 for ; Fri, 15 Feb 2019 02:24:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550197479; bh=DU8CL1zyXXLXMsSSamR3mxRVEo3Xi4RUvaqnPzs1Jwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U6yIkqgs7CswRJ+GniC5RH8HXauaSEx3cBti8RkoG7uLP3DzBwzFLFL+cYbauybFR XUOQn0rbsg8D9j2LuRXJ0VhrxoaB63k2qTzJRdh7wVZNmJslJhN44pAq7PELnmLOjB W2LgTewPhOAYY9rlJpi7QmFB11QWZknYZlwYFNXw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405241AbfBOCOt (ORCPT ); Thu, 14 Feb 2019 21:14:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:54562 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405192AbfBOCOn (ORCPT ); Thu, 14 Feb 2019 21:14:43 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A33C321B68; Fri, 15 Feb 2019 02:14:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550196883; bh=DU8CL1zyXXLXMsSSamR3mxRVEo3Xi4RUvaqnPzs1Jwg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kh+D6A7luG4NJceQ+FZhQIL4ERrUW92d1/PRSD8+8RhnVe5U/+H4zdkzaLPG5d3aE duPQVVvY9P589loySqHflFOwm0flR97OL2Nb5H4RvGEosnV7UnCa2EWBRaZtlPXdGA tLHR6bTU/QpyIwGnKdXP72tX+haBYZuXx7FPeR34= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Silvio Cesare , Timur Tabi , Nicolin Chen , Mark Brown , Xiubo Li , Fabio Estevam , Dan Carpenter , Kees Cook , Will Deacon , Greg KH , Willy Tarreau , Sasha Levin , linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.9 09/27] ASoC: imx-audmux: change snprintf to scnprintf for possible overflow Date: Thu, 14 Feb 2019 21:14:06 -0500 Message-Id: <20190215021424.178979-9-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190215021424.178979-1-sashal@kernel.org> References: <20190215021424.178979-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Silvio Cesare [ Upstream commit c407cd008fd039320d147088b52d0fa34ed3ddcb ] Change snprintf to scnprintf. There are generally two cases where using snprintf causes problems. 1) Uses of size += snprintf(buf, SIZE - size, fmt, ...) In this case, if snprintf would have written more characters than what the buffer size (SIZE) is, then size will end up larger than SIZE. In later uses of snprintf, SIZE - size will result in a negative number, leading to problems. Note that size might already be too large by using size = snprintf before the code reaches a case of size += snprintf. 2) If size is ultimately used as a length parameter for a copy back to user space, then it will potentially allow for a buffer overflow and information disclosure when size is greater than SIZE. When the size is used to index the buffer directly, we can have memory corruption. This also means when size = snprintf... is used, it may also cause problems since size may become large. Copying to userspace is mitigated by the HARDENED_USERCOPY kernel configuration. The solution to these issues is to use scnprintf which returns the number of characters actually written to the buffer, so the size variable will never exceed SIZE. Signed-off-by: Silvio Cesare Cc: Timur Tabi Cc: Nicolin Chen Cc: Mark Brown Cc: Xiubo Li Cc: Fabio Estevam Cc: Dan Carpenter Cc: Kees Cook Cc: Will Deacon Cc: Greg KH Signed-off-by: Willy Tarreau Acked-by: Nicolin Chen Reviewed-by: Kees Cook Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- sound/soc/fsl/imx-audmux.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/sound/soc/fsl/imx-audmux.c b/sound/soc/fsl/imx-audmux.c index fc57da341d61..136df38c4536 100644 --- a/sound/soc/fsl/imx-audmux.c +++ b/sound/soc/fsl/imx-audmux.c @@ -86,49 +86,49 @@ static ssize_t audmux_read_file(struct file *file, char __user *user_buf, if (!buf) return -ENOMEM; - ret = snprintf(buf, PAGE_SIZE, "PDCR: %08x\nPTCR: %08x\n", + ret = scnprintf(buf, PAGE_SIZE, "PDCR: %08x\nPTCR: %08x\n", pdcr, ptcr); if (ptcr & IMX_AUDMUX_V2_PTCR_TFSDIR) - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "TxFS output from %s, ", audmux_port_string((ptcr >> 27) & 0x7)); else - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "TxFS input, "); if (ptcr & IMX_AUDMUX_V2_PTCR_TCLKDIR) - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "TxClk output from %s", audmux_port_string((ptcr >> 22) & 0x7)); else - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "TxClk input"); - ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n"); + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n"); if (ptcr & IMX_AUDMUX_V2_PTCR_SYN) { - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "Port is symmetric"); } else { if (ptcr & IMX_AUDMUX_V2_PTCR_RFSDIR) - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "RxFS output from %s, ", audmux_port_string((ptcr >> 17) & 0x7)); else - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "RxFS input, "); if (ptcr & IMX_AUDMUX_V2_PTCR_RCLKDIR) - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "RxClk output from %s", audmux_port_string((ptcr >> 12) & 0x7)); else - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "RxClk input"); } - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\nData received from %s\n", audmux_port_string((pdcr >> 13) & 0x7)); -- 2.19.1