Re: [Qemu-devel] [PATCH] Fix bug with virtio-9p fsync

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Apr 26, 2011 at 1:14 PM, Sassan Panahinejad <sassan@sassan.me.uk> wrote:
> v9fs_fsync and possibly others break when asked to operate on a directory.
> It does not check fid_type to see if it is operating on a directory and therefore accesses the wrong element of the fs union.
> This error can result in guest applications failing (in my case it was dpkg).
> This patch fixes the issue, although there may be other, similar bugs in virtio-9p.
>
> Signed-off-by: Sassan Panahinejad <sassan@sassan.me.uk>
> ---
>  hw/virtio-9p.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
> index 7e29535..cc4fdc8 100644
> --- a/hw/virtio-9p.c
> +++ b/hw/virtio-9p.c
> @@ -1875,7 +1875,11 @@ static void v9fs_fsync(V9fsState *s, V9fsPDU *pdu)
>         v9fs_post_do_fsync(s, pdu, err);
>         return;
>     }
> -    err = v9fs_do_fsync(s, fidp->fs.fd, datasync);
> +    if (fidp->fid_type == P9_FID_DIR) {
> +        err = v9fs_do_fsync(s, dirfd(fidp->fs.dir), datasync);
> +    } else {
> +        err = v9fs_do_fsync(s, fidp->fs.fd, datasync);
> +    }

What about P9_FID_XATTR, seems like we have the same issue there too?

wstat, lock, and getlock need closer auditing and perhaps fixing.

Stefan