| Message ID | 20240112062221.135681-1-chentao@kylinos.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vfio: Fix NULL pointer dereference in vfio_pci_bus_notifier | expand |
On Fri, 12 Jan 2024 14:22:21 +0800 Kunwu Chan <chentao@kylinos.cn> wrote: > kasprintf() returns a pointer to dynamically allocated memory > which can be NULL upon failure. Ensure the allocation was successful > by checking the pointer validity. > > Signed-off-by: Kunwu Chan <chentao@kylinos.cn> > --- > drivers/vfio/pci/vfio_pci_core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c > index 1cbc990d42e0..74e5b89a3a0c 100644 > --- a/drivers/vfio/pci/vfio_pci_core.c > +++ b/drivers/vfio/pci/vfio_pci_core.c > @@ -2047,6 +2047,8 @@ static int vfio_pci_bus_notifier(struct notifier_block *nb, > pci_name(pdev)); > pdev->driver_override = kasprintf(GFP_KERNEL, "%s", > vdev->vdev.ops->name); > + if (!pdev->driver_override) > + return -ENOMEM; > } else if (action == BUS_NOTIFY_BOUND_DRIVER && > pdev->is_virtfn && physfn == vdev->pdev) { > struct pci_driver *drv = pci_dev_driver(pdev); This is a blocking notifier callback, so errno isn't a proper return value, nor does it accomplish anything. We're into the realm of worrying about small allocation failures here, which I understand essentially cannot happen, but about the best we could do at this point would be to WARN_ON if we weren't able to allocate an override. Thanks, Alex
On 2024/1/12 23:30, Alex Williamson wrote: > On Fri, 12 Jan 2024 14:22:21 +0800 > Kunwu Chan <chentao@kylinos.cn> wrote: > >> kasprintf() returns a pointer to dynamically allocated memory >> which can be NULL upon failure. Ensure the allocation was successful >> by checking the pointer validity. >> >> Signed-off-by: Kunwu Chan <chentao@kylinos.cn> >> --- >> drivers/vfio/pci/vfio_pci_core.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c >> index 1cbc990d42e0..74e5b89a3a0c 100644 >> --- a/drivers/vfio/pci/vfio_pci_core.c >> +++ b/drivers/vfio/pci/vfio_pci_core.c >> @@ -2047,6 +2047,8 @@ static int vfio_pci_bus_notifier(struct notifier_block *nb, >> pci_name(pdev)); >> pdev->driver_override = kasprintf(GFP_KERNEL, "%s", >> vdev->vdev.ops->name); >> + if (!pdev->driver_override) >> + return -ENOMEM; >> } else if (action == BUS_NOTIFY_BOUND_DRIVER && >> pdev->is_virtfn && physfn == vdev->pdev) { >> struct pci_driver *drv = pci_dev_driver(pdev); > > This is a blocking notifier callback, so errno isn't a proper return > value, nor does it accomplish anything. We're into the realm of > worrying about small allocation failures here, which I understand > essentially cannot happen, but about the best we could do at this > point would be to WARN_ON if we weren't able to allocate an override. Thanks for your reply. I'll update v2 patch use WARN_ON to print some callstack msgs when we weren't able to allocate an override. These msgs could reduce some of the worries and help us to find what happed. > Thanks, > > Alex >
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 1cbc990d42e0..74e5b89a3a0c 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -2047,6 +2047,8 @@ static int vfio_pci_bus_notifier(struct notifier_block *nb, pci_name(pdev)); pdev->driver_override = kasprintf(GFP_KERNEL, "%s", vdev->vdev.ops->name); + if (!pdev->driver_override) + return -ENOMEM; } else if (action == BUS_NOTIFY_BOUND_DRIVER && pdev->is_virtfn && physfn == vdev->pdev) { struct pci_driver *drv = pci_dev_driver(pdev);
kasprintf() returns a pointer to dynamically allocated memory which can be NULL upon failure. Ensure the allocation was successful by checking the pointer validity. Signed-off-by: Kunwu Chan <chentao@kylinos.cn> --- drivers/vfio/pci/vfio_pci_core.c | 2 ++ 1 file changed, 2 insertions(+)