Re: [Qemu-devel] [RESEND] [PATCH] hw/9pfs: fix P9_STATS_GEN handling

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

"Kirill A. Shutemov" <kirill@shutemov.name> writes:

> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> Currently we have few issues with P9_STATS_GEN:
>
>  - We don't try to read st_gen anything except files or directories, but
>    still set P9_STATS_GEN bit in st_result_mask. It may mislead client:
>    we present garbage as valid st_gen.

We should return 0 right ? We do 

    memset(v9lstat, 0, sizeof(*v9lstat));

in stat_to_v9stat_dotl

>
>  - If we failed to get valid st_gen with ENOTTY, we ignore error, but
>    still set P9_STATS_GEN bit in st_result_mask.

and have v9lstat.st_gen set to zero 

>
>  - If we failed to get valid st_gen with any other errno, we fail
>    getattr altogether. It's excessive: we block valid client use-cases,
>    like chdir(2) to non-readable directory with execution bit set.
>

Can you explain this in detail ? 

> The patch fixes these issues and cleanup code a bit.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  hw/9pfs/cofile.c           |  4 ----
>  hw/9pfs/virtio-9p-handle.c |  8 +++++++-
>  hw/9pfs/virtio-9p-local.c  | 10 ++++++----
>  hw/9pfs/virtio-9p-proxy.c  |  3 ++-
>  hw/9pfs/virtio-9p.c        | 12 ++++++++++--
>  5 files changed, 25 insertions(+), 12 deletions(-)
>

-aneesh