NULL Pointer Dereference Affecting kernel-rt-debug package, versions <0:4.18.0-553.70.1.rt7.411.el8_10
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Start learning- Snyk IDSNYK-CENTOS8-KERNELRTDEBUG-12898222
- published27 Sept 2025
- disclosed17 Sept 2025
Introduced: 17 Sep 2025
NewCVE-2022-50369 (opens in a new tab)How to fix?
Upgrade Centos:8 kernel-rt-debug to version 0:4.18.0-553.70.1.rt7.411.el8_10 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug package and not the kernel-rt-debug package as distributed by Centos.
See How to fix? for Centos:8 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
drm/vkms: Fix null-ptr-deref in vkms_release()
A null-ptr-deref is triggered when it tries to destroy the workqueue in vkms->output.composer_workq in vkms_release().
KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f] CPU: 5 PID: 17193 Comm: modprobe Not tainted 6.0.0-11331-gd465bff130bf #24 RIP: 0010:destroy_workqueue+0x2f/0x710 ... Call Trace: <TASK> ? vkms_config_debugfs_init+0x50/0x50 [vkms] __devm_drm_dev_alloc+0x15a/0x1c0 [drm] vkms_init+0x245/0x1000 [vkms] do_one_initcall+0xd0/0x4f0 do_init_module+0x1a4/0x680 load_module+0x6249/0x7110 __do_sys_finit_module+0x140/0x200 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0
The reason is that an OOM happened which triggers the destroy of the workqueue, however, the workqueue is alloced in the later process, thus a null-ptr-deref happened. A simple call graph is shown as below:
vkms_init() vkms_create() devm_drm_dev_alloc() __devm_drm_dev_alloc() devm_drm_dev_init() devm_add_action_or_reset() devm_add_action() # an error happened devm_drm_dev_init_release() drm_dev_put() kref_put() drm_dev_release() vkms_release() destroy_workqueue() # null-ptr-deref happened vkms_modeset_init() vkms_output_init() vkms_crtc_init() # where the workqueue get allocated
Fix this by checking if composer_workq is NULL before passing it to the destroy_workqueue() in vkms_release().
References
- https://access.redhat.com/security/cve/CVE-2022-50369
- https://git.kernel.org/stable/c/0b8f390e2251191f1b179cc87f65d54c96565f0d
- https://git.kernel.org/stable/c/1f9836f95271e7acf016667eee0aeae3386f9645
- https://git.kernel.org/stable/c/2fe2a8f40c21161ffe7653cc234e7934db5b7cc5
- https://git.kernel.org/stable/c/57031c474c3a920ea73afeb5dc352e537f5793ee
- https://git.kernel.org/stable/c/596f1ba3987e601e31a5abf1f75ce1d2635aceac