2018-08-03 04:12:49

by jiangyiwen

Subject: [V9fs-developer] [PATCH] net/9p: Modify the problem of BUG_ON judgment

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 <[email protected]>
---
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);
--
1.8.3.1

2018-08-03 04:24:59

by Dominique Martinet

Subject: Re: [V9fs-developer] [PATCH] net/9p: Modify the problem of BUG_ON judgment

jiangyiwen wrote on Fri, Aug 03, 2018:
> 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 <[email protected]>

I'm not sure you've acted on his mail or if you found this
independantly, but this was reported by Dan Carpenter on the list in
June.
Would you mind if I add a tag for him?
Reported-by: Dan Carpenter <[email protected]>

That aside this looks good, I'll take it.

> ---
> 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);

--
Dominique Martinet

2018-08-03 06:19:13

by jiangyiwen

Subject: Re: [V9fs-developer] [PATCH] net/9p: Modify the problem of BUG_ON judgment

On 2018/8/3 12:23, Dominique Martinet wrote:
> jiangyiwen wrote on Fri, Aug 03, 2018:
>> 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 <[email protected]>
>
> I'm not sure you've acted on his mail or if you found this
> independantly, but this was reported by Dan Carpenter on the list in
> June.
> Would you mind if I add a tag for him?
> Reported-by: Dan Carpenter <[email protected]>
>
> That aside this looks good, I'll take it.
>

Sorry, I didn't see it before, I tested this problem a few days ago.
It is true that this problem was discovered first by him. Thank you
for adding him.

>> ---
>> 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);
>

2018-08-03 06:21:00

by piaojun

Subject: Re: [V9fs-developer] [PATCH] net/9p: Modify the problem of BUG_ON judgment

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 <[email protected]>
Acked-by: Jun Piao <[email protected]>
> ---
> 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);
>