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,URIBL_BLOCKED,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 9CFEFC43387 for ; Tue, 8 Jan 2019 19:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 617C620645 for ; Tue, 8 Jan 2019 19:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546976355; bh=kP3xqKMPjF9mdDQili8JQSuUpvPUc/O9wMpOSEfIfhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UGH1G6v5A4CWLaBWCIIiTJRiZbKClVCenjBxG037s2quRZbsp6nmiedqYcBoBlNyX tvHl3pToy48wPQplLk0yGiC5iZ06QQ/Tq3Rdq4p9+BR0VjL8xLOQHvJGWvIQRZTF8D MPgmUyVncdRD2OI6blusLEuBE8Lqthcbl6k3tCX4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732169AbfAHTfH (ORCPT ); Tue, 8 Jan 2019 14:35:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:43852 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730097AbfAHTfC (ORCPT ); Tue, 8 Jan 2019 14:35:02 -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 06B8B20645; Tue, 8 Jan 2019 19:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546976101; bh=kP3xqKMPjF9mdDQili8JQSuUpvPUc/O9wMpOSEfIfhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CILTb9YiRNacdA9vUa3Eq64KCq3VV51sVhzWI1ldAl1V7xHsqC0q45n7pUc2gSp/y H1goTafas1TwqlNYykS1qcGSD0w5xeMiVc3vgO4Y9TzQF12Csl1H87T+mmKj2kYOXn 4K6IYZl8n+TBREVzc2y1Mh9DEJuVme0ApoZkS4E8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Joel Fernandes (Google)" , Kees Cook , Sasha Levin Subject: [PATCH AUTOSEL 4.4 09/28] pstore/ram: Do not treat empty buffers as valid Date: Tue, 8 Jan 2019 14:34:26 -0500 Message-Id: <20190108193445.124251-9-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108193445.124251-1-sashal@kernel.org> References: <20190108193445.124251-1-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 bd21795ce657..679d75a864d0 100644 --- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -445,6 +445,11 @@ 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