CVE-2026-74274

Received Received - Intake

Memory Corruption in Linux Kernel CXL Region Driver

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: cxl/region: Fill first free targets[] slot during auto-discovery Any invalid endpoint decoder pointer in the target array of an active region is not allowed by cxl driver. This means cxl driver always assumes the first p->nr_targets entries of the target array in an auto-assembly region are valid. However, there are scenarios that could leave NULL endpoint decoder pointer holes in the target array. 1. When cxl_cancel_auto_attach() removes an endpoint decoder from a target array, the target slot is set to NULL. If the removed endpoint decoder is not the last element in the target array, the target array will contain a NULL hole. 2. When a auto-assembly region removes an assigned endpoint decoder, if the removed endpoint decoder is not the last element in the target array, always remains a NULL hole in the target array. When a NULL pointer hole exists in a region's target array, it introduces two potential problems: 1. Access an endpoint decoder via a NULL pointer. it always trigger calltrace like that. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] SMP KASAN PTI RIP: 0010:cxl_calc_interleave_pos+0x26/0x810 [cxl_core] Call Trace: <TASK> cxl_region_attach+0xc50/0x2140 [cxl_core] cxl_add_to_region+0x321/0x2330 [cxl_core] discover_region+0x92/0x150 [cxl_port] device_for_each_child+0xf3/0x170 cxl_port_probe+0x150/0x200 [cxl_port] cxl_bus_probe+0x4f/0xa0 [cxl_core] really_probe+0x1c8/0x960 __driver_probe_device+0x323/0x450 driver_probe_device+0x45/0x120 __device_attach_driver+0x15d/0x280 bus_for_each_drv+0x10f/0x190 2. Not having enough valid endpoint decoders attached to an auto-assembly region. if an auto-assembly region is created with lock flag or assigned endpoint decoder with lock flag, which means assigned endpoint decoder will not be reset during detaching, they could re-attach to the auto-assembly region again. But cxl region driver relies on p->nr_targets to verify whether the required number of endpoint decoders has been attached, and NULL endpoint decoder pointers are still counted in that case. To fix above issues, adjust cxl_region_attach_auto() logic to find the first free target slot for endpoint decoder attachment, this ensures NULL holes in the target array are filled, rather than adding new endpoint decoders at the tail of the target array.

CVSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-17

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74274

EUVD

EUVD-2026-59421

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves improper handling of NULL pointers in the CXL (Compute Express Link) region target array during auto-discovery. When endpoint decoders are removed from the target array, NULL holes may remain if the removed decoder is not the last element. This can lead to two issues: accessing a NULL pointer causing a general protection fault, or incorrect counting of valid endpoint decoders due to NULL pointers still being counted in the total.

Detection Guidance

This vulnerability is specific to the Linux kernel's CXL (Compute Express Link) driver and affects systems using CXL regions. Detection requires checking kernel logs for general protection faults related to cxl_calc_interleave_pos or cxl_region_attach functions. Monitor dmesg or system logs for Oops messages indicating NULL pointer dereferences in CXL components.

Impact Analysis

This vulnerability can cause system crashes due to general protection faults when NULL pointers are accessed. It may also lead to incorrect behavior in CXL regions, such as failing to attach the required number of endpoint decoders or improperly resetting locked endpoint decoders during detachment.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it pertains to the Linux kernel's CXL (Compute Express Link) driver functionality. The issue involves NULL pointer dereferences and improper endpoint decoder handling in the cxl driver, which could lead to system crashes or instability but does not involve data privacy or security breaches that would impact regulatory compliance.

Mitigation Strategies

Apply the latest kernel patches that address this issue. If patches are unavailable, avoid using auto-assembly regions with CXL endpoint decoders until the fix is applied. Review existing CXL regions for NULL holes in target arrays and manually correct them if possible.

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