CVE-2026-46264
Analyzed Analyzed - Analysis Complete
Use-after-free in Linux kernel DRM/XE PF sysfs initialization

Publication date: 2026-06-03

Last updated on: 2026-06-09

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: drm/xe/pf: Fix sysfs initialization In case of devm_add_action_or_reset() failure the provided cleanup action will be run immediately on the not yet initialized kobject. This may lead to errors like: [ ] kobject: '(null)' (ff110001393608e0): is not initialized, yet kobject_put() is being called. [ ] WARNING: lib/kobject.c:734 at kobject_put+0xd9/0x250, CPU#0: kworker/0:0/9 [ ] RIP: 0010:kobject_put+0xdf/0x250 [ ] Call Trace: [ ] xe_sriov_pf_sysfs_init+0x21/0x100 [xe] [ ] xe_sriov_pf_init_late+0x87/0x2b0 [xe] [ ] xe_sriov_init_late+0x5f/0x2c0 [xe] [ ] xe_device_probe+0x5f2/0xc20 [xe] [ ] xe_pci_probe+0x396/0x610 [xe] [ ] local_pci_probe+0x47/0xb0 [ ] refcount_t: underflow; use-after-free. [ ] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x68/0xb0, CPU#0: kworker/0:0/9 [ ] RIP: 0010:refcount_warn_saturate+0x68/0xb0 [ ] Call Trace: [ ] kobject_put+0x174/0x250 [ ] xe_sriov_pf_sysfs_init+0x21/0x100 [xe] [ ] xe_sriov_pf_init_late+0x87/0x2b0 [xe] [ ] xe_sriov_init_late+0x5f/0x2c0 [xe] [ ] xe_device_probe+0x5f2/0xc20 [xe] [ ] xe_pci_probe+0x396/0x610 [xe] [ ] local_pci_probe+0x47/0xb0 Fix that by calling kobject_init() and kobject_add() separately and register cleanup action after the kobject is initialized. Also make this cleanup registration a part of the create helper to fix another mistake, as in the loop we were wrongly passing parent kobject while registering cleanup action, and this resulted in some undetected leaks. (cherry picked from commit 98b16727f07e26a5d4de84d88805ce7ffcfdd324)
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Meta Information
Published
2026-06-03
Last Modified
2026-06-09
Generated
2026-06-24
AI Q&A
2026-06-03
EPSS Evaluated
2026-06-22
NVD
CVE-2026-46264
EUVD
EUVD-2026-34126
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 6.19 (inc) to 6.19.4 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Executive Summary

This vulnerability exists in the Linux kernel's drm/xe/pf component related to sysfs initialization. When the function devm_add_action_or_reset() fails, it immediately runs a cleanup action on a kobject that has not yet been initialized. This improper handling can cause errors such as calling kobject_put() on an uninitialized kobject and refcount underflow, leading to use-after-free conditions.

The root cause is that the cleanup action is registered before the kobject is properly initialized, and in some cases, the parent kobject was incorrectly passed during cleanup registration, causing undetected resource leaks. The fix involves initializing and adding the kobject separately before registering the cleanup action, ensuring proper lifecycle management.

Impact Analysis

This vulnerability can lead to kernel errors such as use-after-free and refcount underflow, which may cause system instability or crashes. Improper handling of kernel objects can result in resource leaks and unpredictable behavior in the affected Linux kernel component.

Detection Guidance

This vulnerability can be detected by monitoring kernel logs for specific error messages related to uninitialized kobjects and refcount underflows.

  • Look for log entries containing messages like "kobject: '(null)': is not initialized, yet kobject_put() is being called."
  • Check for warnings such as "refcount_t: underflow; use-after-free."
  • Use the command `dmesg | grep -E 'kobject_put|refcount_warn_saturate'` to filter relevant kernel warnings.
  • Monitor system logs (e.g., /var/log/kern.log or /var/log/messages) for similar warning patterns.
Mitigation Strategies

The vulnerability has been fixed by properly initializing kobjects before registering cleanup actions.

Immediate mitigation involves updating the Linux kernel to a version that includes the fix for this issue.

  • Apply the patch that calls kobject_init() and kobject_add() separately and registers cleanup actions only after initialization.
  • Avoid running vulnerable kernel versions that may trigger use-after-free errors in the drm/xe/pf subsystem.
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