linux-kernel - RE: [PATCH] [v2] nvme: use correct upper limit for tag in nvme_handle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7df20a0b20b44fbe9e62f4c31087a067@h3c.com>
Date:   Sat, 19 Sep 2020 03:15:02 +0000
From:   Tianxianting <tian.xianting@....com>
To:     Keith Busch <kbusch@...nel.org>
CC:     "axboe@...com" <axboe@...com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] [v2] nvme: use correct upper limit for tag in
 nvme_handle_cqe()

Hi Keith,
Thanks a lot for your comments,
I will try to figure out a safe fix for this issue, then for you review:) 

-----Original Message-----
From: Keith Busch [mailto:kbusch@...nel.org] 
Sent: Saturday, September 19, 2020 3:21 AM
To: tianxianting (RD) <tian.xianting@....com>
Cc: axboe@...com; hch@....de; sagi@...mberg.me; linux-nvme@...ts.infradead.org; linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] nvme: use correct upper limit for tag in nvme_handle_cqe()

On Fri, Sep 18, 2020 at 06:44:20PM +0800, Xianting Tian wrote:
> @@ -940,7 +940,9 @@ static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx)
>  	struct nvme_completion *cqe = &nvmeq->cqes[idx];
>  	struct request *req;
>  
> -	if (unlikely(cqe->command_id >= nvmeq->q_depth)) {
> +	if (unlikely(cqe->command_id >=
> +			nvmeq->qid ? nvmeq->dev->tagset.queue_depth :
> +			nvmeq->dev->admin_tagset.queue_depth)) {

Both of these values are set before blk_mq_alloc_tag_set(), so you still have a race. The interrupt handler probably just shouldn't be registered with the queue before the tagset is initialized since there can't be any work for the handler to do before that happens anyway.

The controller is definitely broken, though, and will lead to unavoidable corruption if it's really behaving this way.