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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 7D9D1C282C3 for ; Thu, 24 Jan 2019 19:23:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B0C7218CD for ; Thu, 24 Jan 2019 19:23:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548357781; bh=q6Ric6IfC3Ykq+FqnT57C4kOgvNrjw26eBnzlxnpdO8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pDHNVFMmJG1ffDLTkx8CgS9G3UKp17sjaWALr9AvP1Eli/ySdSBlcVhHPqBAM/BcK 5pJh1rtqvSQMszadnbVmj7TLR1VR5V/XpZ7J6Op80dOGmESfMywWbu+kgmAUv383E/ duB9Q6yG8pM2BrQc+475lQGW5cICqP/xAe2IndB0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729726AbfAXTXA (ORCPT ); Thu, 24 Jan 2019 14:23:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:47646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729698AbfAXTW5 (ORCPT ); Thu, 24 Jan 2019 14:22:57 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 46A76218EA; Thu, 24 Jan 2019 19:22:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548357776; bh=q6Ric6IfC3Ykq+FqnT57C4kOgvNrjw26eBnzlxnpdO8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ETprETeEfSneNwicoJoGHOGM1oY4vKgwieGjY/LzX/nMn+9YanvC4NSyfs6sUFwFJ 5xUUNpKaYtggMI4VWGaCrxpSn6MHm9QNeIXtF8Gf6GF//tDbSnte/VsFVaypsUsayo pjZvgtCpusuoyTCGjfO/F5CBdkM5eDkFswMtdGK0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Joel Fernandes (Google)" , Kees Cook , Sasha Levin Subject: [PATCH 3.18 37/52] pstore/ram: Do not treat empty buffers as valid Date: Thu, 24 Jan 2019 20:20:01 +0100 Message-Id: <20190124190148.752021668@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190124190140.879495253@linuxfoundation.org> References: <20190124190140.879495253@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 30696378f68a9e3dad6bfe55938b112e72af00c2 ] The ramoops backend currently calls persistent_ram_save_old() even if a buffer is empty. While this appears to work, it is does not seem like the right thing to do and could lead to future bugs so lets avoid that. It also prevents misleading prints in the logs which claim the buffer is valid. I got something like: found existing buffer, size 0, start 0 When I was expecting: no valid data in buffer (sig = ...) This bails out early (and reports with pr_debug()), since it's an acceptable state. Signed-off-by: Joel Fernandes (Google) Co-developed-by: Kees Cook Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- fs/pstore/ram_core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c index 288ce45f613e..5ffbf60f5c88 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -484,6 +484,11 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, sig ^= PERSISTENT_RAM_SIG; if (prz->buffer->sig == sig) { + if (buffer_size(prz) == 0) { + pr_debug("found existing empty buffer\n"); + return 0; + } + if (buffer_size(prz) > prz->buffer_size || buffer_start(prz) > buffer_size(prz)) pr_info("found existing invalid buffer, size %zu, start %zu\n", -- 2.19.1