[libvirt] [PATCH] storage: Don't dereference driver object if virStorageSource is not initialized

[John Ferlan]

On 12/06/2017 10:28 AM, Peter Krempa wrote:
> virStorageFileReportBrokenChain uses data from the driver private data
> pointer to print the user and group. This would lead to a crash in call
> paths where we did not initialize the storage backend as recently added
> in commit 24e47ee2b93 to qemuDomainDetermineDiskChain.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1522682
> ---
> 
> Once pushed I'll also backport it to a maint branch of the last release
> if that's desired.
> 
>  src/storage/storage_source.c | 38 ++++++++++++++++++++++++++------------
>  1 file changed, 26 insertions(+), 12 deletions(-)
> 
> diff --git a/src/storage/storage_source.c b/src/storage/storage_source.c
> index 4586ef4ad4..a5df84bae3 100644
> --- a/src/storage/storage_source.c
> +++ b/src/storage/storage_source.c
> @@ -419,19 +419,33 @@ virStorageFileReportBrokenChain(int errcode,
>                                  virStorageSourcePtr src,
>                                  virStorageSourcePtr parent)
>  {
> -    unsigned int access_user = src->drv->uid;
> -    unsigned int access_group = src->drv->gid;
> -
> -    if (src == parent) {
> -        virReportSystemError(errcode,
> -                             _("Cannot access storage file '%s' "
> -                               "(as uid:%u, gid:%u)"),
> -                             src->path, access_user, access_group);
> +
> +    if (src->drv) {
> +        unsigned int access_user = src->drv->uid;
> +        unsigned int access_group = src->drv->gid;
> +
> +        if (src == parent) {
> +            virReportSystemError(errcode,
> +                                 _("Cannot access storage file '%s' "
> +                                   "(as uid:%u, gid:%u)"),
> +                                 src->path, access_user, access_group);
> +        } else {
> +            virReportSystemError(errcode,
> +                                 _("Cannot access backing file '%s' "
> +                                   "of storage file '%s' (as uid:%u, gid:%u)"),
> +                                 src->path, parent->path, access_user, access_group);
> +        }
>      } else {
> -        virReportSystemError(errcode,
> -                             _("Cannot access backing file '%s' "
> -                               "of storage file '%s' (as uid:%u, gid:%u)"),
> -                             src->path, parent->path, access_user, access_group);
> +        if (src == parent) {
> +            virReportSystemError(errcode,
> +                                 _("Cannot access storage file '%s' "),
                                                                      ^
Not that it matters much because it probably won't be seen, but you
could drop the trailing space.


Reviewed-by: John Ferlan <jferlan at redhat.com>

John

> +                                 src->path);
> +        } else {
> +            virReportSystemError(errcode,
> +                                 _("Cannot access backing file '%s' "
> +                                   "of storage file '%s'"),
> +                                 src->path, parent->path);
> +        }
>      }
>  }
>