From patchwork Mon Jul 19 14:53:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 480736 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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 1D322C678C2 for ; Mon, 19 Jul 2021 16:08:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1617A6113A for ; Mon, 19 Jul 2021 16:08:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349241AbhGSP0S (ORCPT ); Mon, 19 Jul 2021 11:26:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:40022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347964AbhGSPXc (ORCPT ); Mon, 19 Jul 2021 11:23:32 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F2C6961264; Mon, 19 Jul 2021 15:59:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626710398; bh=ALUg3I4EgJTJjOYjclxtb3GuqXylJMBR65DGoO+kQf4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VWhDTobLoYu/ppGc0VKLVdu+/PuTuwHKrAaMRq/wuROTz5UAgayRgl4/FD9pVZx8r COFmT2HdcYTz2SNR9cDjUYs80Xe5tLPMRL6Sih38P70O7jEItcrWtRznH9omuNp9a4 LJSxWEXeQxzydfRConU1n+fH1FHntr7WTJWTn/1g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Carpenter , Alexandre Belloni , Sasha Levin Subject: [PATCH 5.10 199/243] rtc: fix snprintf() checking in is_rtc_hctosys() Date: Mon, 19 Jul 2021 16:53:48 +0200 Message-Id: <20210719144947.352753665@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144940.904087935@linuxfoundation.org> References: <20210719144940.904087935@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Dan Carpenter [ Upstream commit 54b909436ede47e0ee07f1765da27ec2efa41e84 ] The scnprintf() function silently truncates the printf() and returns the number bytes that it was able to copy (not counting the NUL terminator). Thus, the highest value it can return here is "NAME_SIZE - 1" and the overflow check is dead code. Fix this by using the snprintf() function which returns the number of bytes that would have been copied if there was enough space and changing the condition from "> NAME_SIZE" to ">= NAME_SIZE". Fixes: 92589c986b33 ("rtc-proc: permit the /proc/driver/rtc device to use other devices") Signed-off-by: Dan Carpenter Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/YJov/pcGmhLi2pEl@mwanda Signed-off-by: Sasha Levin --- drivers/rtc/proc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/proc.c b/drivers/rtc/proc.c index 73344598fc1b..cbcdbb19d848 100644 --- a/drivers/rtc/proc.c +++ b/drivers/rtc/proc.c @@ -23,8 +23,8 @@ static bool is_rtc_hctosys(struct rtc_device *rtc) int size; char name[NAME_SIZE]; - size = scnprintf(name, NAME_SIZE, "rtc%d", rtc->id); - if (size > NAME_SIZE) + size = snprintf(name, NAME_SIZE, "rtc%d", rtc->id); + if (size >= NAME_SIZE) return false; return !strncmp(name, CONFIG_RTC_HCTOSYS_DEVICE, NAME_SIZE);