CVE-2024-56670
Description
From CVE.org
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
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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