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

[Peter Krempa]

On Wed, Dec 06, 2017 at 16:39:27 -0500, John Ferlan wrote:
> 
> 
> 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.

Right, I've just deleted the second line without fixing the whitespace.

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

Thanks.

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