Patchwork Fix bug with virtio-9p fsync

login
register
mail settings
Submitter Sassan Panahinejad
Date April 25, 2011, 5:54 p.m.
Message ID <1303754045-19635-1-git-send-email-sassan@sassan.me.uk>
Download mbox | patch
Permalink /patch/92765/
State New
Headers show

Comments

Sassan Panahinejad - April 25, 2011, 5:54 p.m.
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.
---
 hw/virtio-9p.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
Stefan Hajnoczi - April 26, 2011, 9:18 a.m.
On Mon, Apr 25, 2011 at 6:54 PM, Sassan Panahinejad <sassan@sassan.me.uk> wrote:

Thanks for finding and fixing this.  Please see this wiki page on
contributing patches to QEMU:
http://wiki.qemu.org/Contribute/SubmitAPatch

> 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.
> ---
>  hw/virtio-9p.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)

Missing Signed-off-by:.

> diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
> index 7e29535..09fb5da 100644
> --- a/hw/virtio-9p.c
> +++ b/hw/virtio-9p.c
> @@ -1875,7 +1875,10 @@ 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);

Please follow QEMU coding style and always use {} with if ... else.

Stefan

Patch

diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 7e29535..09fb5da 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -1875,7 +1875,10 @@  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);
     v9fs_post_do_fsync(s, pdu, err);
 }