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(-)
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); + } } }
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
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Udipto Goswami