CVE-2023-54277 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
fbdev: udlfb: Fix endpoint check
The syzbot fuzzer detected a problem in the udlfb driver, caused by an endpoint not having the expected type:
usb 1-1: Read EDID byte 0 failed: -71 usb 1-1: Unable to get valid EDID from device/display ------------[ cut here ]------------
usb 1-1: BOGUS urb xfer, pipe 3 != type 1 WARNING: CPU: 0 PID: 9 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 Modules linked in: CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.4.0-rc1-syzkaller-00016-ga4422ff22142 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 Workqueue: usb_hub_wq hub_event RIP: 0010:usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 ... Call Trace: <TASK> dlfb_submit_urb+0x92/0x180 drivers/video/fbdev/udlfb.c:1980 dlfb_set_video_mode+0x21f0/0x2950 drivers/video/fbdev/udlfb.c:315 dlfb_ops_set_par+0x2a7/0x8d0 drivers/video/fbdev/udlfb.c:1111 dlfb_usb_probe+0x149a/0x2710 drivers/video/fbdev/udlfb.c:1743
The current approach for this issue failed to catch the problem because it only checks for the existence of a bulk-OUT endpoint; it doesn't check whether this endpoint is the one that the driver will actually use.
We can fix the problem by instead checking that the endpoint used by the driver does exist and is bulk-OUT.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability identified as CVE-2023-54277 resides within the Linux kernel's udlfb driver, which manages display devices connected via USB. This issue manifests as a critical endpoint validation flaw that can lead to system instability and potential denial of service conditions. The problem was uncovered through systematic fuzzing conducted by the syzbot fuzzer, which revealed inconsistencies in how the driver handles USB endpoint configurations during display initialization processes. The vulnerability specifically affects the framebuffer device implementation for USB DisplayLink devices, where improper endpoint type validation creates opportunities for system crashes and operational failures.
The technical root cause stems from inadequate endpoint verification within the udlfb driver's USB communication handling logic. When the driver attempts to establish communication with a USB display device, it performs validation checks that only confirm the existence of a bulk-out endpoint without ensuring that this endpoint is actually the one the driver intends to use for data transmission. This validation gap creates a scenario where the driver may attempt to submit USB requests to an endpoint that does not match the expected type, leading to kernel panic conditions. The error message "BOGUS urb xfer, pipe 3 != type 1" specifically indicates a mismatch between the expected USB transfer type and the actual endpoint configuration, where pipe type 3 represents an interrupt endpoint while the driver expects type 1 which corresponds to bulk transfers.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the stability of systems running Linux kernel versions containing this flaw. When triggered, the vulnerability causes kernel oops conditions that result in system instability, requiring manual intervention for recovery. The affected driver operates within the broader USB subsystem of the Linux kernel, specifically in the usb core components located in drivers/usb/core/urb.c, which makes this issue particularly concerning for embedded systems and server environments where USB display connectivity is common. The vulnerability affects systems where USB DisplayLink devices are connected and actively used for display output, creating a potential attack surface for malicious actors who could exploit this condition to cause service disruption or system crashes.
The fix implemented addresses this vulnerability by modifying the endpoint validation logic to specifically check that the endpoint actually used by the driver exists and is properly configured as a bulk-out endpoint rather than merely verifying the presence of any bulk-out endpoint. This approach aligns with security best practices for USB endpoint validation and follows established patterns in kernel security hardening. The solution prevents the driver from proceeding with invalid endpoint configurations that could lead to kernel panics, thereby maintaining system stability and preventing denial of service conditions. This remediation approach demonstrates proper adherence to secure coding principles by ensuring that all endpoint configurations are validated against the specific requirements of the driver's communication patterns. The fix specifically targets the dlfb_submit_urb function in the udlfb.c driver file, ensuring that endpoint type validation occurs before any USB transfer operations are initiated, thus preventing the kernel from attempting invalid USB operations that would otherwise result in system crashes and operational failures.