From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 764B73D76 for ; Thu, 19 Dec 2024 03:47:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734580078; cv=none; b=oyvg3w/qGYOw7xCQ/AtltYMOFd7KIsiCCpFGj21I3ciMGlQ24OFT/IfWvegu6+ISwvVvyGkIKSf5ve1JcJdmX9EC9rxVnXG3nsgh1MMtcPuik2oQ2UfM8wzbHod2IYuLRnrrLfs3VeHhb7vvL3fYsFb4do7MUy/N4y2z1e3RylI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734580078; c=relaxed/simple; bh=ugltAGn01TtmSEkR8WF4OMbe89BVfUOEwgK81KWfKlw=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=XWvYuDiDogK3qz42bR3rYCCWMC02GQjbMS9O2TgUtSzLajQkp8vkvm4MJOpXjFIQFneCs4epQDc2/FDiyZZYbvZCOzdQKZjkp77Ect18ippnbXxqRPxAJNuRCDPeCg78nKyczpe2ASwCNRUE3Zj/CE8evgs/H+YlTyy+F0m2r+E= 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=T8kvhH+F; arc=none smtp.client-ip=115.124.30.130 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="T8kvhH+F" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1734580067; h=Message-ID:Date:MIME-Version:Subject:From:To:Content-Type; bh=wEVMePcBOENQYmMIHVDSuulnFuDhdoUfyduOQjzB4Ws=; b=T8kvhH+FkcIJwkAHFajdkBSv6k8s2kVXM3AZwxhY5kwgKHLBP0tkuufjTr6TfFTFWnTPuSwXbsw9G+P282laRuqP9Fgvlb3rUqjtsoxJ6gOFr96wcwnUH3kTqcABB5VdKIFdj3xt1BrJEsQKd4GvGMj/6Q8TolmflYbxCkm2QtM= Received: from 30.221.145.61(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0WLosBsg_1734580065 cluster:ay36) by smtp.aliyun-inc.com; Thu, 19 Dec 2024 11:47:46 +0800 Message-ID: Date: Thu, 19 Dec 2024 11:47:44 +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 From: Joseph Qi 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> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2024/12/19 10:24, Joseph Qi wrote: > > > 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)){ Moreover, better to leave a space before '{'. Sorry for not pointing out this in my first reply. Thanks, Joseph >> 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; >> } >> >