CVE-2025-21976 Affecting kernel-rt-modules-internal package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL8-KERNELRTMODULESINTERNAL-9622318
  • published2 Apr 2025
  • disclosed1 Apr 2025

Introduced: 1 Apr 2025

NewCVE-2025-21976  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-rt-modules-internal.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules-internal package and not the kernel-rt-modules-internal package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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

fbdev: hyperv_fb: Allow graceful removal of framebuffer

When a Hyper-V framebuffer device is unbind, hyperv_fb driver tries to release the framebuffer forcefully. If this framebuffer is in use it produce the following WARN and hence this framebuffer is never released.

[ 44.111220] WARNING: CPU: 35 PID: 1882 at drivers/video/fbdev/core/fb_info.c:70 framebuffer_release+0x2c/0x40 < snip > [ 44.111289] Call Trace: [ 44.111290] <TASK> [ 44.111291] ? show_regs+0x6c/0x80 [ 44.111295] ? __warn+0x8d/0x150 [ 44.111298] ? framebuffer_release+0x2c/0x40 [ 44.111300] ? report_bug+0x182/0x1b0 [ 44.111303] ? handle_bug+0x6e/0xb0 [ 44.111306] ? exc_invalid_op+0x18/0x80 [ 44.111308] ? asm_exc_invalid_op+0x1b/0x20 [ 44.111311] ? framebuffer_release+0x2c/0x40 [ 44.111313] ? hvfb_remove+0x86/0xa0 [hyperv_fb] [ 44.111315] vmbus_remove+0x24/0x40 [hv_vmbus] [ 44.111323] device_remove+0x40/0x80 [ 44.111325] device_release_driver_internal+0x20b/0x270 [ 44.111327] ? bus_find_device+0xb3/0xf0

Fix this by moving the release of framebuffer and assosiated memory to fb_ops.fb_destroy function, so that framebuffer framework handles it gracefully.

While we fix this, also replace manual registrations/unregistration of framebuffer with devm_register_framebuffer.

CVSS Base Scores

version 3.1