CVE-2024-46760

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtw88: usb: schedule rx work after everything is set up

Right now its possible to hit NULL pointer dereference in rtw_rx_fill_rx_status on hw object and/or its fields because initialization routine can start getting USB replies before rtw_dev is fully setup.

The stack trace looks like this:

rtw_rx_fill_rx_status rtw8821c_query_rx_desc rtw_usb_rx_handler … queue_work rtw_usb_read_port_complete … usb_submit_urb rtw_usb_rx_resubmit rtw_usb_init_rx rtw_usb_probe

So while we do the async stuff rtw_usb_probe continues and calls rtw_register_hw, which does all kinds of initialization (e.g. via ieee80211_register_hw) that rtw_rx_fill_rx_status relies on.

Fix this by moving the first usb_submit_urb after everything is set up.

For me, this bug manifested as: [ 8.893177] rtw_8821cu 1-1:1.2: band wrong, packet dropped [ 8.910904] rtw_8821cu 1-1:1.2: hw->conf.chandef.chan NULL in rtw_rx_fill_rx_status because Im using Larrys backport of rtw88 driver with the NULL checks in rtw_rx_fill_rx_status.

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/25eaef533bf3ccc6fee5067aac16f41f280e343e
• https://git.kernel.org/stable/c/adc539784c98a7cc602cbf557debfc2e7b9be8b3
• https://git.kernel.org/stable/c/c83d464b82a8ad62ec9077637f75d73fe955635a