From nobody Tue Sep 16 20:10:49 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F8CDC4332F for ; Thu, 29 Dec 2022 01:45:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232846AbiL2Bov (ORCPT ); Wed, 28 Dec 2022 20:44:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230106AbiL2Bos (ORCPT ); Wed, 28 Dec 2022 20:44:48 -0500 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 359372DD8 for ; Wed, 28 Dec 2022 17:44:48 -0800 (PST) Received: by mail-pg1-x52b.google.com with SMTP id d10so11525412pgm.13 for ; Wed, 28 Dec 2022 17:44:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=ZPAYQwDWE9OMZ/U/cOHoYvo1QQGJp7a/uZzvsCRbps0=; b=nFcHKhnkpBC8BREMcxP6tbEj+TD9ajmkyJeQtRZZQ/8zkzT5/QZOU78DQ21N+GzqYH CQXOJTtSFRibm/v+SzFg61MduaSpd+9kBPFEwfxmRkSMyd8Uw+jyIdBrkCCr/3WNhkD9 5e6g8pY/n6Towtipvc5j8LuWaEuVoX4/0heST9kOcWC30YYNCB/oo1hUg+DJYMuFBlxx 8lNsSEjSkC4nDBGRC8Mnqjjl6gNx+i4XRQHMKta54ZX+TSftPH3BgAH8gzvmpny1Z347 1qjn6qbwDMQ0FyiyZPn3E7Tqjy1vCRF+3L3ijw3jKeXuHOl4nopIbpcJa8nB+8djRSta E0CA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ZPAYQwDWE9OMZ/U/cOHoYvo1QQGJp7a/uZzvsCRbps0=; b=f0lFdSY5hKkTp+8Of/yvTJeAi9IKO7hyARgFX8cd7FuXfsInPChW50WbqGiRUZgnNw sip9E8gg5Cd30NSQnOfs3vdYjAK3lbXmJjax398KuI01uSL8Ip0N56WTPOxO3rBwxWIZ VOHv/l7IIrFmqvJh1H2D3/vQwqEsZb+OVeWZe0QHmZO/F7e/xZQJBCf7Tibdh/g4i1Rg AhjWf6slgwg8Xkxing8Bd3SDfA7K4rFTlSTpyqpwpWEs+eaqDT9MLd3mK8+5q8qgzwOA DP7jhgcjz23BRvXQgL4LsvN8jJgOmKTEJNsXZjjxArCaqW6u8OP020bUMO9RuQq8YupK +RSg== X-Gm-Message-State: AFqh2kp9HZZkLWxtkjiT3DUrwfKkhCqHuInyuxo1H9RCNnugYED/r3ho KxhOQSc20QC0C4YEKHBuMSNAxg== X-Google-Smtp-Source: AMrXdXvojSXuSoryp/+zW9mksXlqmVI/fQmGd01x2fGKaWw8fg70sKCJgMP5IIIdoaXSU2ynA3ADMw== X-Received: by 2002:a05:6a00:410b:b0:57a:9482:843b with SMTP id bu11-20020a056a00410b00b0057a9482843bmr30916851pfb.5.1672278287678; Wed, 28 Dec 2022 17:44:47 -0800 (PST) Received: from niej-dt-7B47.. (80.251.214.228.16clouds.com. [80.251.214.228]) by smtp.gmail.com with ESMTPSA id 14-20020a62150e000000b005609d3d3008sm5433780pfv.171.2022.12.28.17.44.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Dec 2022 17:44:46 -0800 (PST) From: Jun Nie To: djwong@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Cc: tudor.ambarus@linaro.org Subject: [PATCH] ext4: reject 1k block fs on the first block of disk Date: Thu, 29 Dec 2022 09:45:02 +0800 Message-Id: <20221229014502.2322727-1-jun.nie@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" For 1k-block filesystems, the filesystem starts at block 1, not block 0. If start_fsb is 0, it will be bump up to s_first_data_block. Then ext4_get_group_no_and_offset don't know what to do and return garbage results (blockgroup 2^32-1). The underflow make index exceed es->s_groups_count in ext4_get_group_info() and trigger the BUG_ON. Fixes: 4a4956249dac0 ("ext4: fix off-by-one fsmap error on 1k block filesys= tems") Link: https://syzkaller.appspot.com/bug?id=3D79d5768e9bfe362911ac1a5057a36f= c6b5c30002 Reported-by: syzbot+6be2b977c89f79b6b153@syzkaller.appspotmail.com Signed-off-by: Jun Nie --- fs/ext4/fsmap.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ext4/fsmap.c b/fs/ext4/fsmap.c index 4493ef0c715e..1aef127b0634 100644 --- a/fs/ext4/fsmap.c +++ b/fs/ext4/fsmap.c @@ -702,6 +702,12 @@ int ext4_getfsmap(struct super_block *sb, struct ext4_= fsmap_head *head, if (handlers[i].gfd_dev > head->fmh_keys[0].fmr_device) memset(&dkeys[0], 0, sizeof(struct ext4_fsmap)); =20 + /* + * Re-check the range after above limit operation and reject + * 1K fs on block 0 as fs should start block 1. */ + if (dkeys[0].fmr_physical =3D=3D0 && dkeys[1].fmr_physical =3D=3D 0) + continue; + info.gfi_dev =3D handlers[i].gfd_dev; info.gfi_last =3D false; info.gfi_agno =3D -1; --=20 2.34.1