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

fbdev: Fix vmalloc out-of-bounds write in fast_imageblit

This issue triggers when a userspace program does an ioctl
FBIOPUT_CON2FBMAP by passing console number and frame buffer number.
Ideally this maps console to frame buffer and updates the screen if
console is visible.

As part of mapping it has to do resize of console according to frame
buffer info. if this resize fails and returns from vc_do_resize() and
continues further. At this point console and new frame buffer are mapped
and sets display vars. Despite failure still it continue to proceed
updating the screen at later stages where vc_data is related to previous
frame buffer and frame buffer info and display vars are mapped to new
frame buffer and eventully leading to out-of-bounds write in
fast_imageblit(). This bheviour is excepted only when fg_console is
equal to requested console which is a visible console and updates screen
with invalid struct references in fbcon_putcs().
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 05 Sep 2025 14:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Fri, 05 Sep 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Thu, 04 Sep 2025 15:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix vmalloc out-of-bounds write in fast_imageblit This issue triggers when a userspace program does an ioctl FBIOPUT_CON2FBMAP by passing console number and frame buffer number. Ideally this maps console to frame buffer and updates the screen if console is visible. As part of mapping it has to do resize of console according to frame buffer info. if this resize fails and returns from vc_do_resize() and continues further. At this point console and new frame buffer are mapped and sets display vars. Despite failure still it continue to proceed updating the screen at later stages where vc_data is related to previous frame buffer and frame buffer info and display vars are mapped to new frame buffer and eventully leading to out-of-bounds write in fast_imageblit(). This bheviour is excepted only when fg_console is equal to requested console which is a visible console and updates screen with invalid struct references in fbcon_putcs().
Title fbdev: Fix vmalloc out-of-bounds write in fast_imageblit
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-09-04T15:32:39.856Z

Reserved: 2025-04-16T04:51:24.032Z

Link: CVE-2025-38685

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-09-04T16:15:36.397

Modified: 2025-09-05T17:47:24.833

Link: CVE-2025-38685

cve-icon Redhat

Severity : Important

Publid Date: 2025-09-04T00:00:00Z

Links: CVE-2025-38685 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-09-05T14:02:49Z