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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46935C433EF for ; Sat, 30 Apr 2022 03:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382137AbiD3Da3 (ORCPT ); Fri, 29 Apr 2022 23:30:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232757AbiD3DaV (ORCPT ); Fri, 29 Apr 2022 23:30:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 753913D48C; Fri, 29 Apr 2022 20:27:00 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EC99A624D4; Sat, 30 Apr 2022 03:26:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BF49C385AD; Sat, 30 Apr 2022 03:26:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651289219; bh=d3ZW5fNPK57eX66J9ylKtIPChK1LOQBQAo/4SDkWPvk=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=RBq81V1B0zC1wsouKSpwHcYn/RAVKgyizDbYM3/yVAZUOp35whj2HgfAFJgUfrRA9 KcmTRSIvFGUMxmSSHn5dZn1Lh0QP007kCZMsrNrkwdrHFWeBXLNWy0F/kxSi+BY+7H JXPxxOgtE03yzUinsNtfAI2wc2Srm4MgxKbRUGvuuMnZgTzyLLZaW1rY8vR152J6AB oUzNcKul34iJI0xwW5mZaFonY4WO02G1vRI+WBpsOZH3nbr/HADkYgy+YFVQwedsRv MPxItXG2YhmYjIefDA943fD4PdKLLxtHUdn4brKm5TuHufjUVBbO9eGhcp/OenTLZs rMBDcenRcxfyw== Received: by mail-wm1-f47.google.com with SMTP id p189so5541698wmp.3; Fri, 29 Apr 2022 20:26:59 -0700 (PDT) X-Gm-Message-State: AOAM531fJLJegFSxB1thi9tfS83Yr3hxGnNF9l1Ovb2p97dEHKeOpRnt A+j5oR12HHJO3l/hNlRW6GnTVa3B2myBYMqBB64= X-Google-Smtp-Source: ABdhPJzEDelgZYI9HaASTigWNgH5drnhUAvbr85xTlM+Xv8ERFusnHEgo96dz4tPdMyNM7ga0jrYWBKiJe3/P395BX8= X-Received: by 2002:a05:600c:384f:b0:393:e79f:a146 with SMTP id s15-20020a05600c384f00b00393e79fa146mr5823746wmr.102.1651289217537; Fri, 29 Apr 2022 20:26:57 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a5d:64e7:0:0:0:0:0 with HTTP; Fri, 29 Apr 2022 20:26:56 -0700 (PDT) In-Reply-To: References: <20220418173923.193173-1-tadeusz.struk@linaro.org> From: Namjae Jeon Date: Sat, 30 Apr 2022 12:26:56 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] exfat: check if cluster num is valid To: Tadeusz Struk Cc: Sungjong Seo , linux-fsdevel@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 2022-04-22 14:54 GMT+09:00, Namjae Jeon : > 2022-04-19 2:39 GMT+09:00, Tadeusz Struk : > Hi Tadeusz, > >> Syzbot reported slab-out-of-bounds read in exfat_clear_bitmap. >> This was triggered by reproducer calling truncate with size 0, >> which causes the following trace: >> >> BUG: KASAN: slab-out-of-bounds in exfat_clear_bitmap+0x147/0x490 >> fs/exfat/balloc.c:174 >> Read of size 8 at addr ffff888115aa9508 by task syz-executor251/365 >> >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118 >> print_address_description+0x81/0x3c0 mm/kasan/report.c:233 >> __kasan_report mm/kasan/report.c:419 [inline] >> kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436 >> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309 >> exfat_clear_bitmap+0x147/0x490 fs/exfat/balloc.c:174 >> exfat_free_cluster+0x25a/0x4a0 fs/exfat/fatent.c:181 >> __exfat_truncate+0x99e/0xe00 fs/exfat/file.c:217 >> exfat_truncate+0x11b/0x4f0 fs/exfat/file.c:243 >> exfat_setattr+0xa03/0xd40 fs/exfat/file.c:339 >> notify_change+0xb76/0xe10 fs/attr.c:336 >> do_truncate+0x1ea/0x2d0 fs/open.c:65 > Could you please share how to reproduce this ? Ping, If you apply this patch to your source, there is a problem. You need to add +1 to EXFAT_DATA_CLUSTER_COUNT(sbi). and please use is_valid_cluster() to check if cluster is valid instead of it. > > Thanks. >> >> Add checks to validate if cluster number is within valid range in >> exfat_clear_bitmap() and exfat_set_bitmap() >> >> Cc: Namjae Jeon >> Cc: Sungjong Seo >> Cc: linux-fsdevel@vger.kernel.org >> Cc: stable@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> >> Link: >> https://syzkaller.appspot.com/bug?id=50381fc73821ecae743b8cf24b4c9a04776f767c >> Reported-by: syzbot+a4087e40b9c13aad7892@syzkaller.appspotmail.com >> Fixes: 1e49a94cf707 ("exfat: add bitmap operations") >> Signed-off-by: Tadeusz Struk >> --- >> fs/exfat/balloc.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c >> index 03f142307174..4ed81f86f993 100644 >> --- a/fs/exfat/balloc.c >> +++ b/fs/exfat/balloc.c >> @@ -149,6 +149,9 @@ int exfat_set_bitmap(struct inode *inode, unsigned >> int >> clu, bool sync) >> struct exfat_sb_info *sbi = EXFAT_SB(sb); >> >> WARN_ON(clu < EXFAT_FIRST_CLUSTER); >> + if (clu > EXFAT_DATA_CLUSTER_COUNT(sbi)) >> + return -EINVAL; >> + >> ent_idx = CLUSTER_TO_BITMAP_ENT(clu); >> i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx); >> b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx); >> @@ -167,6 +170,9 @@ void exfat_clear_bitmap(struct inode *inode, unsigned >> int clu, bool sync) >> struct exfat_mount_options *opts = &sbi->options; >> >> WARN_ON(clu < EXFAT_FIRST_CLUSTER); >> + if (clu > EXFAT_DATA_CLUSTER_COUNT(sbi)) >> + return; >> + >> ent_idx = CLUSTER_TO_BITMAP_ENT(clu); >> i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx); >> b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx); >> -- >> 2.35.1 >> >> >