[PATCH v2] net/9p/trans_virtio.c: add null terminal for mount tag

piaojun
2018-08-02T01:49:49Z

chan->tag is Non-null terminated which will result in printing messy code
when debugging code. So we should add '\0' for tag to make the code more
convenient and robust. In addition, I drop char->tag_len to simplify the
code.

Signed-off-by: Jun Piao <piaojun@huawei.com>
---
net/9p/trans_virtio.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index d422bfc..0fe9c37 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -89,10 +89,8 @@ struct virtio_chan {
unsigned long p9_max_pages;
/* Scatterlist: can be too big for stack. */
struct scatterlist sg[VIRTQUEUE_NUM];
-
- int tag_len;
/*
- * tag name to identify a mount Non-null terminated
+ * tag name to identify a mount null terminated
*/
char *tag;

@@ -529,10 +527,9 @@ static ssize_t p9_mount_tag_show(struct device *dev,
vdev = dev_to_virtio(dev);
chan = vdev->priv;

- memcpy(buf, chan->tag, chan->tag_len);
- buf[chan->tag_len] = 0;
+ memcpy(buf, chan->tag, strlen(chan->tag) + 1);

- return chan->tag_len + 1;
+ return strlen(chan->tag) + 1;
}

static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
@@ -585,7 +582,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
err = -EINVAL;
goto out_free_vq;
}
- tag = kmalloc(tag_len, GFP_KERNEL);
+ tag = kzalloc(tag_len + 1, GFP_KERNEL);
if (!tag) {
err = -ENOMEM;
goto out_free_vq;
@@ -594,7 +591,6 @@ static int p9_virtio_probe(struct virtio_device *vdev)
virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
tag, tag_len);
chan->tag = tag;
- chan->tag_len = tag_len;
err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
if (err) {
goto out_free_tag;
@@ -654,8 +650,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)

mutex_lock(&virtio_9p_lock);
list_for_each_entry(chan, &virtio_chan_list, chan_list) {
- if (!strncmp(devname, chan->tag, chan->tag_len) &&
- strlen(devname) == chan->tag_len) {
+ if (!strncmp(devname, chan->tag, strlen(chan->tag) + 1)) {
if (!chan->inuse) {
chan->inuse = true;
found = 1;
--