| Message ID | 20240110095814.7626-1-quic_ugoswami@quicinc.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 12783c0b9e2c7915a50d5ec829630ff2da50472c |
| Headers | show |
| Series | [v5] usb: core: Prevent null pointer dereference in update_port_device_state | expand |
On Wed, Jan 10, 2024 at 03:28:14PM +0530, Udipto Goswami wrote: > Currently, the function update_port_device_state gets the usb_hub from > udev->parent by calling usb_hub_to_struct_hub. > However, in case the actconfig or the maxchild is 0, the usb_hub would > be NULL and upon further accessing to get port_dev would result in null > pointer dereference. > > Fix this by introducing an if check after the usb_hub is populated. > > Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state") > Cc: stable@vger.kernel.org > Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> > --- > v5: Addressed nit picks in commit and the comment. > v4: Fixed minor mistakes in the comment. > v3: Re-wrote the comment for better context. > v2: Introduced comment for the if check & CC'ed stable. Reviewed-by: Alan Stern <stern@rowland.harvard.edu> > drivers/usb/core/hub.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index ffd7c99e24a3..48409d51ea43 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -2053,9 +2053,19 @@ static void update_port_device_state(struct usb_device *udev) > > if (udev->parent) { > hub = usb_hub_to_struct_hub(udev->parent); > - port_dev = hub->ports[udev->portnum - 1]; > - WRITE_ONCE(port_dev->state, udev->state); > - sysfs_notify_dirent(port_dev->state_kn); > + > + /* > + * The Link Layer Validation System Driver (lvstest) > + * has a test step to unbind the hub before running the > + * rest of the procedure. This triggers hub_disconnect > + * which will set the hub's maxchild to 0, further > + * resulting in usb_hub_to_struct_hub returning NULL. > + */ > + if (hub) { > + port_dev = hub->ports[udev->portnum - 1]; > + WRITE_ONCE(port_dev->state, udev->state); > + sysfs_notify_dirent(port_dev->state_kn); > + } > } > } > > -- > 2.17.1 >
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index ffd7c99e24a3..48409d51ea43 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2053,9 +2053,19 @@ static void update_port_device_state(struct usb_device *udev) if (udev->parent) { hub = usb_hub_to_struct_hub(udev->parent); - port_dev = hub->ports[udev->portnum - 1]; - WRITE_ONCE(port_dev->state, udev->state); - sysfs_notify_dirent(port_dev->state_kn); + + /* + * The Link Layer Validation System Driver (lvstest) + * has a test step to unbind the hub before running the + * rest of the procedure. This triggers hub_disconnect + * which will set the hub's maxchild to 0, further + * resulting in usb_hub_to_struct_hub returning NULL. + */ + if (hub) { + port_dev = hub->ports[udev->portnum - 1]; + WRITE_ONCE(port_dev->state, udev->state); + sysfs_notify_dirent(port_dev->state_kn); + } } }
Currently, the function update_port_device_state gets the usb_hub from udev->parent by calling usb_hub_to_struct_hub. However, in case the actconfig or the maxchild is 0, the usb_hub would be NULL and upon further accessing to get port_dev would result in null pointer dereference. Fix this by introducing an if check after the usb_hub is populated. Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state") Cc: stable@vger.kernel.org Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> --- v5: Addressed nit picks in commit and the comment. v4: Fixed minor mistakes in the comment. v3: Re-wrote the comment for better context. v2: Introduced comment for the if check & CC'ed stable. drivers/usb/core/hub.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)