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 3A2E8C433F5 for ; Fri, 22 Apr 2022 05:55:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232772AbiDVF5w (ORCPT ); Fri, 22 Apr 2022 01:57:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232691AbiDVF5u (ORCPT ); Fri, 22 Apr 2022 01:57:50 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9586A2FB; Thu, 21 Apr 2022 22:54:57 -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 ams.source.kernel.org (Postfix) with ESMTPS id F0B50B82974; Fri, 22 Apr 2022 05:54:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B12B1C385AA; Fri, 22 Apr 2022 05:54:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650606893; bh=bUrwNa2jPgsgJxQkoG5r227zZatdq91cfQWCFa1pTUc=; h=In-Reply-To:References:From:Date:Subject:To:Cc:From; b=IKKl4bekyTRerar8LEgfm2sWhYaTy65ntzCBXTmlkjSeXw0ig56ou0blltKZGah2U e/W8JJbrLQLv9DlVZnuSu6hsPUqYkIMuMxPNvJrEYL6j+Y7rS+k1Rrhgqj2xev5SuB +ICisZxzj8ogizJ5du1+3E6WmJisMkDRX/RBPc/SbSm8XDUbIjz0PRFkw52ftd1A2r XGSi5TwROwToDMOC/wMoRxiC/qenY0DLShpRnrygDA4JsKSGa04ez4+77I1ycl2QBT SabmEGL2/4YDRnU7dQ/p3YOcIFThShuI/8eRyQv9HBLW2nBTLWgiqisd15rhtiEHI/ vIyxO71DPZz9w== Received: by mail-wm1-f47.google.com with SMTP id q20so4456535wmq.1; Thu, 21 Apr 2022 22:54:53 -0700 (PDT) X-Gm-Message-State: AOAM5339Y3SIUj57/2xC4xCGojiNZAqirmdB83SvswCDESJYsML/39Xz xEyeJSeXaTPvjwroBVDNfei3eiU+Hu1vvUcJDxE= X-Google-Smtp-Source: ABdhPJzA5pKXGtSgCP8euSF4E86K804hiGfu+B7CoBJFdhlDoGVeeXI0gHS8+quTHu87bDT4vhNdS6R9/IaCxgzAPZQ= X-Received: by 2002:a05:600c:3503:b0:38f:fbd7:1f0d with SMTP id h3-20020a05600c350300b0038ffbd71f0dmr2439802wmq.170.1650606891969; Thu, 21 Apr 2022 22:54:51 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a5d:6b8a:0:0:0:0:0 with HTTP; Thu, 21 Apr 2022 22:54:51 -0700 (PDT) In-Reply-To: <20220418173923.193173-1-tadeusz.struk@linaro.org> References: <20220418173923.193173-1-tadeusz.struk@linaro.org> From: Namjae Jeon Date: Fri, 22 Apr 2022 14:54:51 +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-kernel@vger.kernel.org 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 ? 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 > >