Use After Free Affecting kernel-obs-build package, versions <5.14.21-150500.55.88.1


Severity

Recommended
high

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-SLES155-KERNELOBSBUILD-8524588
  • published18 Dec 2024
  • disclosed17 Dec 2024

Introduced: 17 Dec 2024

NewCVE-2024-49924  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.5 kernel-obs-build to version 5.14.21-150500.55.88.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-obs-build package and not the kernel-obs-build package as distributed by SLES. See How to fix? for SLES:15.5 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

fbdev: pxafb: Fix possible use after free in pxafb_task()

In the pxafb_probe function, it calls the pxafb_init_fbinfo function, after which &fbi->task is associated with pxafb_task. Moreover, within this pxafb_init_fbinfo function, the pxafb_blank function within the &pxafb_ops struct is capable of scheduling work.

If we remove the module which will call pxafb_remove to make cleanup, it will call unregister_framebuffer function which can call do_unregister_framebuffer to free fbi->fb through put_fb_info(fb_info), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows:

CPU0 CPU1

                               | pxafb_task

pxafb_remove | unregister_framebuffer(info) | do_unregister_framebuffer(fb_info) | put_fb_info(fb_info) | // free fbi->fb | set_ctrlr_state(fbi, state) | __pxafb_lcd_power(fbi, 0) | fbi->lcd_power(on, &fbi->fb.var) | //use fbi->fb

Fix it by ensuring that the work is canceled before proceeding with the cleanup in pxafb_remove.

Note that only root user can remove the driver at runtime.

CVSS Scores

version 3.1