CVE-2024-56670 usb: gadget: u_serial: Fix the issue that gs_start_io crashed due to accessing null pointer
A race condition in the Linux kernel USB gadget driver causes a null pointer dereference and system crash when disconnecting during open operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-56670?
CVE-2024-56670 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: u_serial: Fix the issue that gs_start_io crashed due to accessing null pointer
Considering that in some extreme cases, when u_serial driver is accessed by multiple threads, Thread A is executing the open operation and calling the gs_open, Thread B is executing the disconnect operation and calling the gserial_disconnect function,The port->port_usb pointer will be set to NULL.
E.g. Thread A Thread B gs_open() gadget_unbind_driver() gs_start_io() composite_disconnect() gs_start_rx() gserial_disconnect() ... ... spin_unlock(&port->port_lock) status = usb_ep_queue() spin_lock(&port->port_lock) spin_lock(&port->port_lock) port->port_usb = NULL gs_free_requests(port->port_usb->in) spin_unlock(&port->port_lock) Crash
This causes thread A to access a null pointer (port->port_usb is null) when calling the gs_free_requests function, causing a crash.
If port_usb is NULL, the release request will be skipped as it will be done by gserial_disconnect.
So add a null pointer check to gs_start_io before attempting to access the value of the pointer port->port_usb.
Call trace: gs_start_io+0x164/0x25c gs_open+0x108/0x13c tty_open+0x314/0x638 chrdev_open+0x1b8/0x258 do_dentry_open+0x2c4/0x700 vfs_open+0x2c/0x3c path_openat+0xa64/0xc60 do_filp_open+0xb8/0x164 do_sys_openat2+0x84/0xf0 __arm64_sys_openat+0x70/0x9c invoke_syscall+0x58/0x114 el0_svc_common+0x80/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x38/0x68
Weakness: CWE-476
Which versions are affected by CVE-2024-56670?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-56670?
Apply the vendor's patch.
Is CVE-2024-56670 being exploited?
There is no known exploitation of CVE-2024-56670 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-54759, AZL-54868, BELL-CVE-2024-56670, DEBIAN-CVE-2024-56670, GHSA-32x8-xhwp-vhg9, UBUNTU-CVE-2024-56670.