From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relayaws-01.paragon-software.com (relayaws-01.paragon-software.com [35.157.23.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B1D642E2852 for ; Thu, 28 May 2026 14:03:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.157.23.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779976999; cv=none; b=L/JeWi6oQXl3bQd1OFmos/ayJNs3Idrdkgv6aiLdp2zH/qnkxIO9oJj53DvodE5S0A+D8lPRP7Dru2jSrtA1B4LU4EwwLUgj8RUhwucRtgkYg2sQJ5sdBe/groMRs1FS6wG0xX/gySzX6TOagRkiPbRtlZC6rj+9hYJLrZAeuK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779976999; c=relaxed/simple; bh=aLAoOS3eSCbGlFJXm0E02lp+fcweaZUG+J76HCW0jvE=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=Equmr/ob75JRVHbK5nf1cc7Gn1h00uo+Rs5kdbt8cCrf7v2gxxJyTRLqa0AsVwJY0tH3FSIMebWccM0tJ3hzfOZWaKieWD9T9R2leI4XGSiyI6pNOXROWwann5NjCBdliXvL4cp15VjehTKkX3wYeG8DJIoek255JwuiXqjnUpg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com; spf=pass smtp.mailfrom=paragon-software.com; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b=OeZFBcDg; arc=none smtp.client-ip=35.157.23.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=paragon-software.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=paragon-software.com header.i=@paragon-software.com header.b="OeZFBcDg" Received: from relayfre-01.paragon-software.com (relayfre-01.paragon-software.com [176.12.100.13]) by relayaws-01.paragon-software.com (Postfix) with ESMTPS id 3DA7E26; Thu, 28 May 2026 14:03:18 +0000 (UTC) Authentication-Results: relayaws-01.paragon-software.com; dkim=pass (1024-bit key; unprotected) header.d=paragon-software.com header.i=@paragon-software.com header.b=OeZFBcDg; dkim-atps=neutral Received: from dlg2.mail.paragon-software.com (vdlg-exch-02.paragon-software.com [172.30.1.105]) by relayfre-01.paragon-software.com (Postfix) with ESMTPS id E0C201D44; Thu, 28 May 2026 14:03:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paragon-software.com; s=mail; t=1779976995; bh=FbSpeyDe76XdZEgVbC4mDjj5knCEy+ahsGDVLbayXcU=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=OeZFBcDgH+AkC2S4bW5rK9vY/7/QSL2YAmVD3zzeu8uBTeZe3Msl7h9ouGpQZ9Uqc XhD0L4MnBHPIT1Ee248CyQ+NemGvL0Mclrd78hGpNAL46i5UVBStDOqCr22Gh1jjjJ 0LaVNREwvjBCwQEZGBk/I6WyrkLBZB3rgfkP9shk= Received: from [192.168.95.128] (172.30.20.180) by vdlg-exch-02.paragon-software.com (172.30.1.105) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.7; Thu, 28 May 2026 17:03:14 +0300 Message-ID: <71e5333c-bb8a-4886-bfa1-e1b4cb8ea451@paragon-software.com> Date: Thu, 28 May 2026 16:03:13 +0200 Precedence: bulk X-Mailing-List: ntfs3@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] fs/ntfs3: reject out-of-range evcn in mi_enum_attr() To: fra-build , CC: , , References: <20260427035025.38158-1-zhanxusheng@xiaomi.com> <20260515082305.54624-1-fra@build.local> Content-Language: en-US From: Konstantin Komarov In-Reply-To: <20260515082305.54624-1-fra@build.local> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: vobn-exch-01.paragon-software.com (172.30.72.13) To vdlg-exch-02.paragon-software.com (172.30.1.105) On 5/15/26 10:23, fra-build wrote: > From: Zhan Xusheng > > In mi_enum_attr(), the start/end VCN validation for non-resident > attributes is: > > if (svcn > evcn + 1) goto out; > > When evcn is U64_MAX the "evcn + 1" expression wraps to 0 and any > svcn passes the check. For evcn values close to U64_MAX (but not > equal to it) the right-hand side is still a meaningless near-wrap > upper bound, so a malformed on-disk attribute with svcn == 0 and > evcn near U64_MAX can pass mi_enum_attr() unrejected. > > VCN (virtual cluster number) is a cluster index, so any valid evcn > is bounded by the volume's total cluster count, which ntfs3 holds > in sbi->used.bitmap.nbits (set up in ntfs_init_from_boot() before > any caller of mi_enum_attr() runs). Reject evcn values that fall > outside this range; this rejects all out-of-range evcn values, > not just U64_MAX, and as a side effect prevents the "evcn + 1" > wraparound entirely. > > Fixes: 013ff63b6494 ("fs/ntfs3: Add more attributes checks in mi_enum_attr()") > Signed-off-by: Zhan Xusheng > --- > fs/ntfs3/record.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/fs/ntfs3/record.c b/fs/ntfs3/record.c > index 32bdb034c2a3..4379446bcf96 100644 > --- a/fs/ntfs3/record.c > +++ b/fs/ntfs3/record.c > @@ -202,7 +202,7 @@ struct ATTRIB *mi_enum_attr(struct ntfs_inode *ni, struct mft_inode *mi, > u32 used = le32_to_cpu(rec->used); > u32 t32, off, asize, prev_type; > u16 t16; > - u64 data_size, alloc_size, tot_size; > + u64 svcn, evcn, data_size, alloc_size, tot_size; > > if (!attr) { > u32 total = le32_to_cpu(rec->total); > @@ -310,8 +310,17 @@ struct ATTRIB *mi_enum_attr(struct ntfs_inode *ni, struct mft_inode *mi, > if (t32 && le16_to_cpu(attr->name_off) + t32 > t16) > goto out; > > - /* Check start/end vcn. */ > - if (le64_to_cpu(attr->nres.svcn) > le64_to_cpu(attr->nres.evcn) + 1) > + /* > + * Check start/end vcn. evcn must be a valid cluster index, i.e. > + * less than the volume's total cluster count (sbi->used.bitmap.nbits); > + * rejecting it here also keeps "svcn > evcn + 1" meaningful, since > + * evcn == U64_MAX would wrap "evcn + 1" to 0. svcn does not need > + * its own bound: once evcn < nbits, "svcn > evcn + 1" implies > + * svcn <= nbits. > + */ > + svcn = le64_to_cpu(attr->nres.svcn); > + evcn = le64_to_cpu(attr->nres.evcn); > + if (evcn >= mi->sbi->used.bitmap.nbits || svcn > evcn + 1) > goto out; > > data_size = le64_to_cpu(attr->nres.data_size); Hello, This patch doesn't apply as-is - during internal testing it caused a number of failures. I believe the cause is empty non-resident attributes, which are legitimately encoded with svcn=0 and evcn=U64_MAX (a -1 sentinel for no allocated clusters). The new evcn >= sbi->used.bitmap.nbits check rejects those valid attributes. The U64_MAX wraparound you're guarding against is real, but it needs to be handled without rejecting the empty-attribute sentinel. Not applied yet. Thanks. Regards, Konstantin