storage: Don't dereference driver object if virStorageSource is not initialized

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

Posted by Peter Krempa 7 years, 5 months ago

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

-- 
2.15.0

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

Posted by John Ferlan 7 years, 5 months ago


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@redhat.com>

John

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

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

Posted by Peter Krempa 7 years, 5 months ago

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@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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