Messages in this thread Patch in this message | | | From | Udipto Goswami <> | Subject | [PATCH v3] usb: core: Prevent null pointer dereference in update_port_device_state | Date | Tue, 9 Jan 2024 11:47:08 +0530 |
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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> --- v3: Re-wrote the comment for better context. v2: Introduced comment for the if check & CC'ed stable.
drivers/usb/core/hub.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index ffd7c99e24a3..6b514546e59b 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2053,9 +2053,23 @@ 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 procedure of unbinding the hub before running + * the rest of the procedure. This triggers + * hub_disconnect will set the hub's maxchild to 0. + * This would result usb_hub_to_struct_hub in this + * function to return NULL. + * + * Add if check to avoid running into NULL pointer + * de-reference. + */ + 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
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