[v2] vfio/pci: Fix a use-after-free issue

[PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Zhenzhong Duan 2 years, 8 months ago

vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
Fix it by allocating a dup of vbasedev->name and then free the dup.

Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
v2: "toke" -> "token", Cedric
    Update with Alex suggested change

 hw/vfio/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index bf27a3990564..73874a94de12 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         qemu_uuid_unparse(&vdev->vf_token, uuid);
         name = g_strdup_printf("%s vf_token=%s", vbasedev->name, uuid);
     } else {
-        name = vbasedev->name;
+        name = g_strdup(vbasedev->name);
     }
 
     ret = vfio_get_device(group, name, vbasedev, errp);
-- 
2.34.1

Re: [PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Philippe Mathieu-Daudé 2 years, 8 months ago

On 17/5/23 04:46, Zhenzhong Duan wrote:
> vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
> Fix it by allocating a dup of vbasedev->name and then free the dup.
> 
> Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
> v2: "toke" -> "token", Cedric
>      Update with Alex suggested change
> 
>   hw/vfio/pci.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Matthew Rosato 2 years, 8 months ago

On 5/16/23 10:46 PM, Zhenzhong Duan wrote:
> vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
> Fix it by allocating a dup of vbasedev->name and then free the dup.
> 
> Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>

Also verified that this resolves an issue seen on s390, as we were seeing not just garbage logs but QEMU crashes in certain cases e.g. during device unplug.  Thanks!

> ---
> v2: "toke" -> "token", Cedric
>     Update with Alex suggested change
> 
>  hw/vfio/pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index bf27a3990564..73874a94de12 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>          qemu_uuid_unparse(&vdev->vf_token, uuid);
>          name = g_strdup_printf("%s vf_token=%s", vbasedev->name, uuid);
>      } else {
> -        name = vbasedev->name;
> +        name = g_strdup(vbasedev->name);
>      }
>  
>      ret = vfio_get_device(group, name, vbasedev, errp);

Re: [PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Alex Williamson 2 years, 8 months ago

On Tue, 23 May 2023 13:00:53 -0400
Matthew Rosato <mjrosato@linux.ibm.com> wrote:

> On 5/16/23 10:46 PM, Zhenzhong Duan wrote:
> > vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
> > Fix it by allocating a dup of vbasedev->name and then free the dup.
> > 
> > Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
> > Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>  
> 
> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> 
> Also verified that this resolves an issue seen on s390, as we were
> seeing not just garbage logs but QEMU crashes in certain cases e.g.
> during device unplug.  Thanks!

Thanks for the testing and reminder, I'll get a pull request out for
this.  Thanks,

Alex

> > ---
> > v2: "toke" -> "token", Cedric
> >     Update with Alex suggested change
> > 
> >  hw/vfio/pci.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > index bf27a3990564..73874a94de12 100644
> > --- a/hw/vfio/pci.c
> > +++ b/hw/vfio/pci.c
> > @@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev,
> > Error **errp) qemu_uuid_unparse(&vdev->vf_token, uuid);
> >          name = g_strdup_printf("%s vf_token=%s", vbasedev->name,
> > uuid); } else {
> > -        name = vbasedev->name;
> > +        name = g_strdup(vbasedev->name);
> >      }
> >  
> >      ret = vfio_get_device(group, name, vbasedev, errp);  
>

Re: [PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Alex Williamson 2 years, 8 months ago

On Tue, 23 May 2023 11:17:47 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> On Tue, 23 May 2023 13:00:53 -0400
> Matthew Rosato <mjrosato@linux.ibm.com> wrote:
> 
> > On 5/16/23 10:46 PM, Zhenzhong Duan wrote:  
> > > vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
> > > Fix it by allocating a dup of vbasedev->name and then free the dup.
> > > 
> > > Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
> > > Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> > > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>    
> > 
> > Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
> > 
> > Also verified that this resolves an issue seen on s390, as we were
> > seeing not just garbage logs but QEMU crashes in certain cases e.g.
> > during device unplug.  Thanks!  
> 
> Thanks for the testing and reminder, I'll get a pull request out for
> this.  Thanks,

Actually Cedric volunteered to bundle this with some pending patches,
so...

Acked-by: Alex Williamson <alex.williamson@redhat.com>

> > > ---
> > > v2: "toke" -> "token", Cedric
> > >     Update with Alex suggested change
> > > 
> > >  hw/vfio/pci.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > > index bf27a3990564..73874a94de12 100644
> > > --- a/hw/vfio/pci.c
> > > +++ b/hw/vfio/pci.c
> > > @@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev,
> > > Error **errp) qemu_uuid_unparse(&vdev->vf_token, uuid);
> > >          name = g_strdup_printf("%s vf_token=%s", vbasedev->name,
> > > uuid); } else {
> > > -        name = vbasedev->name;
> > > +        name = g_strdup(vbasedev->name);
> > >      }
> > >  
> > >      ret = vfio_get_device(group, name, vbasedev, errp);    
> >   
>

Re: [PATCH v2] vfio/pci: Fix a use-after-free issue

Posted by Cédric Le Goater 2 years, 8 months ago

On 5/17/23 04:46, Zhenzhong Duan wrote:
> vbasedev->name is freed wrongly which leads to garbage VFIO trace log.
> Fix it by allocating a dup of vbasedev->name and then free the dup.
> 
> Fixes: 2dca1b37a7 ("vfio/pci: add support for VF token")
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.

> ---
> v2: "toke" -> "token", Cedric
>      Update with Alex suggested change
> 
>   hw/vfio/pci.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index bf27a3990564..73874a94de12 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2994,7 +2994,7 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
>           qemu_uuid_unparse(&vdev->vf_token, uuid);
>           name = g_strdup_printf("%s vf_token=%s", vbasedev->name, uuid);
>       } else {
> -        name = vbasedev->name;
> +        name = g_strdup(vbasedev->name);
>       }
>   
>       ret = vfio_get_device(group, name, vbasedev, errp);