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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 3A4AAC43465 for ; Fri, 18 Sep 2020 02:33:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 058AF22208 for ; Fri, 18 Sep 2020 02:33:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600396395; bh=AVpRSkgj0eO6IkQtoEcXFT1DLNyNXuMgutww47Zi4pk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ls0fbT7JcbVhoR105sQ+fZ1l/KGH64/nXRN5MPG8ElP7WEF9t95AO/3FrPYQGQ18Y yXtKzGtRDg8/zWVLdV1x42x9ALMeLGF42dLjhfUyXsq1Rgxobbs8R1siWt2oVXRh5i EmDwDV4v++o3fo1tUDQyuS54zOBdBcgplQd96qYc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726222AbgIRCdO (ORCPT ); Thu, 17 Sep 2020 22:33:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:41416 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729005AbgIRCNw (ORCPT ); Thu, 17 Sep 2020 22:13:52 -0400 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 5CCC82389E; Fri, 18 Sep 2020 02:13:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395231; bh=AVpRSkgj0eO6IkQtoEcXFT1DLNyNXuMgutww47Zi4pk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L45HNhhWyX7lasyN39wxcLO2MrkIlO3lvaf4ZkuGLd7U9gOe217bGa3lBuFGzFMDE a5A8Spa/Kc38jo7Kso/RjC+FYvDu+BiCB4eE2GlLfpqMWpMvfQb9qr4hHJN091E+3X NL3On6BGHvWPqJPKzw2zjm6SmENVtgo0dyT8A24w= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Christophe JAILLET , Chuck Lever , Sasha Levin , linux-nfs@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 076/127] SUNRPC: Fix a potential buffer overflow in 'svc_print_xprts()' Date: Thu, 17 Sep 2020 22:11:29 -0400 Message-Id: <20200918021220.2066485-76-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918021220.2066485-1-sashal@kernel.org> References: <20200918021220.2066485-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christophe JAILLET [ Upstream commit b25b60d7bfb02a74bc3c2d998e09aab159df8059 ] 'maxlen' is the total size of the destination buffer. There is only one caller and this value is 256. When we compute the size already used and what we would like to add in the buffer, the trailling NULL character is not taken into account. However, this trailling character will be added by the 'strcat' once we have checked that we have enough place. So, there is a off-by-one issue and 1 byte of the stack could be erroneously overwridden. Take into account the trailling NULL, when checking if there is enough place in the destination buffer. While at it, also replace a 'sprintf' by a safer 'snprintf', check for output truncation and avoid a superfluous 'strlen'. Fixes: dc9a16e49dbba ("svc: Add /proc/sys/sunrpc/transport files") Signed-off-by: Christophe JAILLET [ cel: very minor fix to documenting comment Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- net/sunrpc/svc_xprt.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index 7e5f849b44cdb..b293827b2a583 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -103,8 +103,17 @@ void svc_unreg_xprt_class(struct svc_xprt_class *xcl) } EXPORT_SYMBOL_GPL(svc_unreg_xprt_class); -/* - * Format the transport list for printing +/** + * svc_print_xprts - Format the transport list for printing + * @buf: target buffer for formatted address + * @maxlen: length of target buffer + * + * Fills in @buf with a string containing a list of transport names, each name + * terminated with '\n'. If the buffer is too small, some entries may be + * missing, but it is guaranteed that all lines in the output buffer are + * complete. + * + * Returns positive length of the filled-in string. */ int svc_print_xprts(char *buf, int maxlen) { @@ -117,9 +126,9 @@ int svc_print_xprts(char *buf, int maxlen) list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) { int slen; - sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload); - slen = strlen(tmpstr); - if (len + slen > maxlen) + slen = snprintf(tmpstr, sizeof(tmpstr), "%s %d\n", + xcl->xcl_name, xcl->xcl_max_payload); + if (slen >= sizeof(tmpstr) || len + slen >= maxlen) break; len += slen; strcat(buf, tmpstr); -- 2.25.1