From patchwork Mon Jul 19 14:53:53 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: 480522 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 4E4D7C07E95 for ; Mon, 19 Jul 2021 16:22:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 397A6613EB for ; Mon, 19 Jul 2021 16:22:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347680AbhGSPlp (ORCPT ); Mon, 19 Jul 2021 11:41:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:57516 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348752AbhGSPf3 (ORCPT ); Mon, 19 Jul 2021 11:35:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3F4576187E; Mon, 19 Jul 2021 16:14:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626711257; bh=ALUg3I4EgJTJjOYjclxtb3GuqXylJMBR65DGoO+kQf4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y+HMszVDm1hCKOkzLwZETZTfNc1rdO8wiQ+Mq8IQkMtS+YHKC4Z9K2MG83wNfGuu7 j6wPcPS0MiL4lKAs/KTYAmBsOxxI0mo0IxUn/g/i6xR7xgrzIgxz44h0Bvh6yhZrXH H3dSGs5h4n4uvQZ3p2TRRsRCY4l9RefkSu+aMRms= 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 5.13 287/351] rtc: fix snprintf() checking in is_rtc_hctosys() Date: Mon, 19 Jul 2021 16:53:53 +0200 Message-Id: <20210719144954.529465956@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144944.537151528@linuxfoundation.org> References: <20210719144944.537151528@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);