CVE-2021-47169

/// Technical description

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

serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait'

In 'rp2_probe', the driver registers 'rp2_uart_interrupt' then calls

'rp2_fw_cb' through 'request_firmware_nowait'. In 'rp2_fw_cb', if the

firmware don't exists, function just return without initializing ports

of 'rp2_card'. But now the interrupt handler function has been

registered, and when an interrupt comes, 'rp2_uart_interrupt' may access

those ports then causing NULL pointer dereference or other bugs.

Because the driver does some initialization work in 'rp2_fw_cb', in

order to make the driver ready to handle interrupts, 'request_firmware'

should be used instead of asynchronous 'request_firmware_nowait'.

This report reveals it:

INFO: trying to register non-static key.

the code is fine but needs lockdep annotation.

turning off the locking correctness validator.

CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.19.177-gdba4159c14ef-dirty #45

Har

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References