From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 A91737082F for ; Thu, 19 Dec 2024 02:24:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734575101; cv=none; b=auE74JyC/coqPSw41Dpd582oMT2CrwNhrfH9Hjwx1M0KPAU8CBK5RCNMdvVEFLkiK4YX/sglZ8TGAijTuae3V73xuIb60QEq3DBz6CU6yZVIslx0HcuxsJ6I0Gdt8XNF01sfo+zt9l1yosm3ss0JddSc0QAO6RHlZ1SA8cQYW9g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734575101; c=relaxed/simple; bh=ZbArbbV3yorjTKFyb36xndw6Gkgc1uZVkmF/s99xooM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eQAKpfdJEPG4Z8b7PigDQbgZ0IbJHV/irjPPFLBBm8KhzSNX5YN0FAbL9otOyO1/bZclIiz5IZz9BlDGelY2/Ri1HggHFjHeebexshNDP0jufarqQPQXLXa8c1xyzInYTVBy0wWncfQsi2C2wOvkDExSi2oK5+S8/TnO7EzQIy0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=acog5kxW; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="acog5kxW" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1734575095; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Ck4ON6qKb1rZXZEhZ7LwxnXEdLKblYXLYD8/jclut8c=; b=acog5kxWfZOuOLFqpsaIO8ZJdL+YRny9fVL83mP8sM/xxiz8JoViHJxwcYtkGj259rWbK/9oPPsvUX15sNiNnRvq8KUOR5vIAfrrM+mEvqeQyJa9Hg49hgCtb3eDi7KSkdTeRsMG2Y8/8ZNiKgzuhitZ/53QpDANewGRpHLlAJw= Received: from 30.221.145.61(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0WLoZtHq_1734575093 cluster:ay36) by smtp.aliyun-inc.com; Thu, 19 Dec 2024 10:24:54 +0800 Message-ID: Date: Thu, 19 Dec 2024 10:24:53 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] ocfs2: fix slab-use-after-free due to dangling pointer dqi_priv To: Dennis Lam , mark@fasheh.com, jlbec@evilplan.org, akpm Cc: linux-kernel@vger.kernel.org, ocfs2-devel@lists.linux.dev, syzbot+d173bf8a5a7faeede34c@syzkaller.appspotmail.com References: <20241218023924.22821-2-dennis.lamerice@gmail.com> From: Joseph Qi In-Reply-To: <20241218023924.22821-2-dennis.lamerice@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2024/12/18 10:39, Dennis Lam wrote: > When mounting ocfs2 and then remounting it as read-only, a > slab-use-after-free occurs after the user uses a syscall to > quota_getnextquota. Specifically, sb_dqinfo(sb, type)->dqi_priv is the > dangling pointer. > > During the remounting process, the pointer dqi_priv is freed but is > never set as null leaving it to to be accessed. Additionally, the > read-only option for remounting sets the DQUOT_SUSPENDED flag instead of > setting the DQUOT_USAGE_ENABLED flags. Moreover, later in the process of > getting the next quota, the function ocfs2_get_next_id is called and > only checks the quota usage flags and not the quota suspended flags. > > To fix this, I set dqi_priv to null when it is freed after remounting > with read-only and put a check for DQUOT_SUSPENDED in ocfs2_get_next_id. > > Signed-off-by: Dennis Lam > Reported-by: syzbot+d173bf8a5a7faeede34c@syzkaller.appspotmail.com > Tested-by: syzbot+d173bf8a5a7faeede34c@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6731d26f.050a0220.1fb99c.014b.GAE@google.com/T/ Fixes: 8f9e8f5fcc05 ("ocfs2: Fix Q_GETNEXTQUOTA for filesystem without quotas") Cc: Reviewed-by: Joseph Qi > --- > Changes in v2: > - replaced dquot suspended check with !sb_has_quota_active instead > - link to v1: https://lore.kernel.org/lkml/20241215035828.106936-2-dennis.lamerice@gmail.com/ > > fs/ocfs2/quota_global.c | 2 +- > fs/ocfs2/quota_local.c | 1 + > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c > index 2b0daced98eb..096b799d60a0 100644 > --- a/fs/ocfs2/quota_global.c > +++ b/fs/ocfs2/quota_global.c > @@ -893,7 +893,7 @@ static int ocfs2_get_next_id(struct super_block *sb, struct kqid *qid) > int status = 0; > > trace_ocfs2_get_next_id(from_kqid(&init_user_ns, *qid), type); > - if (!sb_has_quota_loaded(sb, type)) { > + if (!sb_has_quota_active(sb, type)){ > status = -ESRCH; > goto out; > } > diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c > index 73d3367c533b..2956d888c131 100644 > --- a/fs/ocfs2/quota_local.c > +++ b/fs/ocfs2/quota_local.c > @@ -867,6 +867,7 @@ static int ocfs2_local_free_info(struct super_block *sb, int type) > brelse(oinfo->dqi_libh); > brelse(oinfo->dqi_lqi_bh); > kfree(oinfo); > + info->dqi_priv = NULL; > return status; > } >