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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 069E1C43387 for ; Tue, 8 Jan 2019 19:33:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C14442176F for ; Tue, 8 Jan 2019 19:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975981; bh=I6sIGRbLxUoN5H26RkCyWXo10trpRo76osjr4rXjLag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=h8acJIVEUOR41mqwuGBa3LFrFHvsGG/oq86ItryA50ZFT7cINqFJOTLB2jK8tkFbY SmLNFfzR0jI/TN8/8NCFt+F990gf7VUicmsf6Z7eKDL68E9NS7pVhOYFKqPhMuyaHX 9d7YGDJNj2exqymPqNhNLJzo+ZTkAd0Z1jkwY2/A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731479AbfAHTdA (ORCPT ); Tue, 8 Jan 2019 14:33:00 -0500 Received: from mail.kernel.org ([198.145.29.99]:41656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731488AbfAHTcx (ORCPT ); Tue, 8 Jan 2019 14:32:53 -0500 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 3A1BC20645; Tue, 8 Jan 2019 19:32:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975972; bh=I6sIGRbLxUoN5H26RkCyWXo10trpRo76osjr4rXjLag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xnRXw4x0qnb7bm4UEDpKZpBj4TH/EMm3oeDQvtECwvlHogQWE7/1t2LjM/hg7Ln5c YMWWjQyNGyeWRabcN/6jvYIAGC7jGFixJ+0QwTn+b3qVYcDMkXDNxbgHen9qOXW5yA 7i+5esikW3BBw9UtBEgiNjir7BoJLGwsHwyEz8JY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Joel Fernandes (Google)" , Kees Cook , Sasha Levin Subject: [PATCH AUTOSEL 4.14 17/53] pstore/ram: Do not treat empty buffers as valid Date: Tue, 8 Jan 2019 14:31:45 -0500 Message-Id: <20190108193222.123316-17-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108193222.123316-1-sashal@kernel.org> References: <20190108193222.123316-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Joel Fernandes (Google)" [ 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 ecdb3baa1283..11e558efd61e 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -488,6 +488,11 @@ 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