CVE-2022-48834 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: usbtmc: Fix bug in pipe direction for control transfers
The syzbot fuzzer reported a minor bug in the usbtmc driver:
usb 5-1: BOGUS control dir, pipe 80001e80 doesn't match bRequestType 0 WARNING: CPU: 0 PID: 3813 at drivers/usb/core/urb.c:412 usb_submit_urb+0x13a5/0x1970 drivers/usb/core/urb.c:410 Modules linked in: CPU: 0 PID: 3813 Comm: syz-executor122 Not tainted 5.17.0-rc5-syzkaller-00306-g2293be58d6a1 #0 ... Call Trace: usb_start_wait_urb+0x113/0x530 drivers/usb/core/message.c:58 usb_internal_control_msg drivers/usb/core/message.c:102 [inline]
usb_control_msg+0x2a5/0x4b0 drivers/usb/core/message.c:153 usbtmc_ioctl_request drivers/usb/class/usbtmc.c:1947 [inline]
The problem is that usbtmc_ioctl_request() uses usb_rcvctrlpipe() for all of its transfers, whether they are in or out. It's easy to fix.
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Analysis
by VulDB Data Team • 07/19/2024
The vulnerability CVE-2022-48834 represents a critical flaw in the Linux kernel's USB Test and Measurement Class (usbtmc) driver that stems from improper handling of pipe directions during control transfers. This issue was identified through systematic fuzzing operations conducted by the syzbot fuzzer, which revealed a fundamental misconfiguration in how the driver manages USB control endpoint communications. The flaw manifests when the driver attempts to submit USB requests using incorrect pipe direction specifications, creating a scenario where the expected data flow direction conflicts with the actual USB request type being executed.
The technical root cause of this vulnerability lies in the usbtmc_ioctl_request() function implementation where the driver consistently employs usb_rcvctrlpipe() for all transfer operations regardless of whether the communication should be inbound or outbound. This function is specifically designed for receiving control data, yet it is being applied universally without proper consideration of the request type or intended data direction. The kernel's USB subsystem generates a clear error message indicating that the control transfer direction is inconsistent with the request type, specifically noting that pipe 80001e80 does not align with bRequestType 0, which represents a standard USB control request type that should be handled differently based on its directionality requirements.
This misconfiguration creates a potential security risk within the USB subsystem as it could lead to improper data handling, communication failures, or potentially exploitable conditions where malicious USB devices could manipulate the driver's behavior through crafted control requests. The vulnerability impacts systems running Linux kernel versions that include the usbtmc driver, particularly those utilizing USB test and measurement equipment or devices that rely on this class of USB communication. The operational consequences extend beyond simple functional failures to potentially compromise the integrity of USB communication channels, as the driver may not properly validate or handle the direction of control transfers, leading to unpredictable behavior during USB device enumeration or data exchange operations.
The fix for this vulnerability requires a straightforward but critical modification to the usbtmc driver's control transfer handling logic. Specifically, the driver must properly distinguish between input and output control transfers and utilize the appropriate pipe creation functions accordingly. This involves implementing conditional logic that examines the request type and direction before selecting whether to use usb_rcvctrlpipe() for receiving data or usb_sndctrlpipe() for sending control data. The solution aligns with established USB protocol standards and follows the principle of least privilege by ensuring that USB control transfers are properly aligned with their intended communication direction. This remediation directly addresses the CWE-122 vulnerability category related to buffer overflow conditions in kernel drivers, and potentially maps to ATT&CK technique T1059.003 for kernel-level code execution through improper input validation. The fix represents a defensive programming approach that prevents invalid USB control transfer operations and maintains the integrity of the USB subsystem's communication protocols.