---
id: CVE-2022-50511
title: 'lib/fonts: fix undefined behavior in bit shift for get_default_font'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  lib/fonts: fix undefined behavior in bit shift for get_default_font

  Shifting signed 32-bit value by 31 bits is undefined, so changing
  significant bit to unsigned.  The…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    e039929e36818507e90901edae87f6fa8bc81093
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    c9a9aa02f0fa3318e0ae5774f404419a1b4759ca
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    e83b47580a0738361772d6f24286adfdaba57e36
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    9c14a85e18a58c102ec223144b7edb5b345c1bea
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    890d91b31f4874361e0df047f57d268a7021cb12
  - >-
    Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 <
    6fe888c4d2fb174408e4540bb2d5602b9f507f90
  - Linux 2.6.23
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T20:12:46.317948Z'
published: '2025-10-07'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:20:50.224Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2022-50511'
references:
  - url: 'https://git.kernel.org/stable/c/e039929e36818507e90901edae87f6fa8bc81093'
  - url: 'https://git.kernel.org/stable/c/c9a9aa02f0fa3318e0ae5774f404419a1b4759ca'
  - url: 'https://git.kernel.org/stable/c/e83b47580a0738361772d6f24286adfdaba57e36'
  - url: 'https://git.kernel.org/stable/c/9c14a85e18a58c102ec223144b7edb5b345c1bea'
  - url: 'https://git.kernel.org/stable/c/890d91b31f4874361e0df047f57d268a7021cb12'
  - url: 'https://git.kernel.org/stable/c/6fe888c4d2fb174408e4540bb2d5602b9f507f90'
tags:
  - cve.org
epss: 0.00161
epssPercentile: 0.05312
ingestedAt: '2026-11-05T22:38:31.744Z'
---

## Overview

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

lib/fonts: fix undefined behavior in bit shift for get_default_font

Shifting signed 32-bit value by 31 bits is undefined, so changing
significant bit to unsigned.  The UBSAN warning calltrace like below:

UBSAN: shift-out-of-bounds in lib/fonts/fonts.c:139:20
left shift of 1 by 31 places cannot be represented in type 'int'
 <TASK>
 dump_stack_lvl+0x7d/0xa5
 dump_stack+0x15/0x1b
 ubsan_epilogue+0xe/0x4e
 __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c
 get_default_font+0x1c7/0x1f0
 fbcon_startup+0x347/0x3a0
 do_take_over_console+0xce/0x270
 do_fbcon_takeover+0xa1/0x170
 do_fb_registered+0x2a8/0x340
 fbcon_fb_registered+0x47/0xe0
 register_framebuffer+0x294/0x4a0
 __drm_fb_helper_initial_config_and_unlock+0x43c/0x880 [drm_kms_helper]
 drm_fb_helper_initial_config+0x52/0x80 [drm_kms_helper]
 drm_fbdev_client_hotplug+0x156/0x1b0 [drm_kms_helper]
 drm_fbdev_generic_setup+0xfc/0x290 [drm_kms_helper]
 bochs_pci_probe+0x6ca/0x772 [bochs]
 local_pci_probe+0x4d/0xb0
 pci_device_probe+0x119/0x320
 really_probe+0x181/0x550
 __driver_probe_device+0xc6/0x220
 driver_probe_device+0x32/0x100
 __driver_attach+0x195/0x200
 bus_for_each_dev+0xbb/0x120
 driver_attach+0x27/0x30
 bus_add_driver+0x22e/0x2f0
 driver_register+0xa9/0x190
 __pci_register_driver+0x90/0xa0
 bochs_pci_driver_init+0x52/0x1000 [bochs]
 do_one_initcall+0x76/0x430
 do_init_module+0x61/0x28a
 load_module+0x1f82/0x2e50
 __do_sys_finit_module+0xf8/0x190
 __x64_sys_finit_module+0x23/0x30
 do_syscall_64+0x58/0x80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
 </TASK>

## Affected

- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < e039929e36818507e90901edae87f6fa8bc81093`
- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < c9a9aa02f0fa3318e0ae5774f404419a1b4759ca`
- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < e83b47580a0738361772d6f24286adfdaba57e36`
- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < 9c14a85e18a58c102ec223144b7edb5b345c1bea`
- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < 890d91b31f4874361e0df047f57d268a7021cb12`
- `Linux >= c81f717cb9e0bd91dc4b98753cb2705ab0fe2801 < 6fe888c4d2fb174408e4540bb2d5602b9f507f90`
- `Linux 2.6.23`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.