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 A0DA9C43466 for ; Fri, 18 Sep 2020 02:44:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C55923444 for ; Fri, 18 Sep 2020 02:44:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600397056; bh=dd0qtlhGR+BuXIEjFCLdHvdAATNJgb10wbQgvOO26c8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JCWheAxc5SMFQ9/UH9c92k6y69GQNUdovBnYXWjSqYGvVTtXtpz5E8tEGvH5UCic2 YdDhY1JVfFqf5B/sfduqWjT4cClZYKDWDMAd+owI3tuVj6O9yMmwd1iTG9/j6dEJS9 woS1ISz2UQZYLpMqf6OCBGiNQbpiZgzx+TQTjqY8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730104AbgIRCn6 (ORCPT ); Thu, 17 Sep 2020 22:43:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:35512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727527AbgIRCKl (ORCPT ); Thu, 17 Sep 2020 22:10:41 -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 85E802311A; Fri, 18 Sep 2020 02:10:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395040; bh=dd0qtlhGR+BuXIEjFCLdHvdAATNJgb10wbQgvOO26c8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TS9aa9HCgMaGIbhWhcFisuPFuwT1/eAN57lgkgaam6Gw3euV+16B9yoVjWbNVhv14 tZ3yhKdxmaNgSkmQQIqprt7enwweION/vGeD1I8HKWDkhO3C2OF/ZsLBCmAdVisGry e6QjuO7MlYj5vZ1+54c2BOosxqzdFEHJwBpu75rw= 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 4.19 130/206] SUNRPC: Fix a potential buffer overflow in 'svc_print_xprts()' Date: Thu, 17 Sep 2020 22:06:46 -0400 Message-Id: <20200918020802.2065198-130-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020802.2065198-1-sashal@kernel.org> References: <20200918020802.2065198-1-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-nfs@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 c8ee8e801edb8..709c082dc9059 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