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usb: core: Prevent null pointer dereference in update_port_device_state

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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: 83cb2604f6 ("usb: core: add sysfs entry for usb device state")
Cc: stable@vger.kernel.org
Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20240110095814.7626-1-quic_ugoswami@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Udipto Goswami 2024-01-10 15:28:14 +05:30 committed by Greg Kroah-Hartman
parent 7c4650ded4
commit 12783c0b9e
1 changed files with 13 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

16
drivers/usb/core/hub.c
View file

@ -2053,9 +2053,19 @@ static void update_port_device_state(struct usb_device *udev)
if (udev->parent) { if (udev->parent) {
hub = usb_hub_to_struct_hub(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);
}
} }
} }