Bug 2404104 (CVE-2025-39967) - CVE-2025-39967 kernel: fbcon: fix integer overflow in fbcon_do_set_font
Summary: CVE-2025-39967 kernel: fbcon: fix integer overflow in fbcon_do_set_font
Keywords:
Status: NEW
Alias: CVE-2025-39967
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-10-15 08:02 UTC by OSIDB Bzimport
Modified: 2025-10-16 11:53 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2025-10-15 08:02:21 UTC
In the Linux kernel, the following vulnerability has been resolved:

fbcon: fix integer overflow in fbcon_do_set_font

Fix integer overflow vulnerabilities in fbcon_do_set_font() where font
size calculations could overflow when handling user-controlled font
parameters.

The vulnerabilities occur when:
1. CALC_FONTSZ(h, pitch, charcount) performs h * pith * charcount
   multiplication with user-controlled values that can overflow.
2. FONT_EXTRA_WORDS * sizeof(int) + size addition can also overflow
3. This results in smaller allocations than expected, leading to buffer
   overflows during font data copying.

Add explicit overflow checking using check_mul_overflow() and
check_add_overflow() kernel helpers to safety validate all size
calculations before allocation.


Note You need to log in before you can comment on or make changes to this bug.