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Subject: Re: [V9fs-developer] [PATCH] net/9p: Modify the problem of BUG_ON
 judgment
To:     jiangyiwen <jiangyiwen@huawei.com>,
        Eric Van Hensbergen <ericvh@gmail.com>,
        Ron Minnich <rminnich@sandia.gov>,
        Latchesar Ionkov <lucho@ionkov.net>,
        Dominique Martinet <asmadeus@codewreck.org>
References: <5B63D5F6.6080109@huawei.com>
CC:     <v9fs-developer@lists.sourceforge.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        <netdev@vger.kernel.org>
From:   piaojun <piaojun@huawei.com>
Message-ID: <5B63F3D1.3020408@huawei.com>
Date:   Fri, 3 Aug 2018 14:18:57 +0800
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LGTM

On 2018/8/3 12:11, jiangyiwen wrote:
> Because the value of limit is VIRTQUEUE_NUM, if index is equal to
> limit, it will cause sg array out of bounds, so correct the judgement
> of BUG_ON.
> 
> Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Acked-by: Jun Piao <piaojun@huawei.com>
> ---
>  net/9p/trans_virtio.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 6265d1d..08264ba 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -191,7 +191,7 @@ static int pack_sg_list(struct scatterlist *sg, int start,
>  		s = rest_of_page(data);
>  		if (s > count)
>  			s = count;
> -		BUG_ON(index > limit);
> +		BUG_ON(index >= limit);
>  		/* Make sure we don't terminate early. */
>  		sg_unmark_end(&sg[index]);
>  		sg_set_buf(&sg[index++], data, s);
> @@ -236,6 +236,7 @@ static int p9_virtio_cancel(struct p9_client *client, struct p9_req_t *req)
>  		s = PAGE_SIZE - data_off;
>  		if (s > count)
>  			s = count;
> +		BUG_ON(index >= limit);
>  		/* Make sure we don't terminate early. */
>  		sg_unmark_end(&sg[index]);
>  		sg_set_page(&sg[index++], pdata[i++], s, data_off);
>