Re: [PATCH] virtiofs: include a newline in sysfs tag

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Apr 25, 2024 at 06:44:00AM -0400, Brian Foster wrote:
> The internal tag string doesn't contain a newline. Append one when
> emitting the tag via sysfs.
> 
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
> 
> Hi all,
> 
> I just noticed this and it seemed a little odd to me compared to typical
> sysfs output, but maybe it was intentional..? Easy enough to send a
> patch either way.. thoughts?

Hi Brian,
Orthogonal to the newline issue, sysfs_emit(buf, "%s", fs->tag) is
needed to prevent format string injection. Please mention this in the
commit description. I'm afraid I introduced that bug, sorry!

Regarding newline, I'm concerned that adding a newline might break
existing programs. Unless there is a concrete need to have the newline,
I would keep things as they are.

Stefan

> 
> Brian
> 
>  fs/fuse/virtio_fs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 322af827a232..bb3e941b9503 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -170,7 +170,7 @@ static ssize_t tag_show(struct kobject *kobj,
>  {
>  	struct virtio_fs *fs = container_of(kobj, struct virtio_fs, kobj);
>  
> -	return sysfs_emit(buf, fs->tag);
> +	return sysfs_emit(buf, "%s\n", fs->tag);
>  }
>  
>  static struct kobj_attribute virtio_fs_tag_attr = __ATTR_RO(tag);
> -- 
> 2.44.0
> 

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