---
id: CVE-2025-38214
title: 'fbdev: Fix fb_set_var to prevent null-ptr-deref in fb_videomode_to_var'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fbdev: Fix fb_set_var to prevent null-ptr-deref in fb_videomode_to_var

  If fb_add_videomode() in fb_set_var() fails to allocate memory for
  fb_videomode, later it may le…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    ee20216f12d9482cd70e44dae5e7fabb38367c71
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    fab201d72fde38d081e2c5d4ad25595c535b7b22
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1a10d91766eb6ddfd5414e4785611e33a4fe0f9b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    ff0e037241173b574b385bff53d67567b9816db5
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    3ca78032a388a0795201792b36e6fc9b6e6e8eed
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    b3071bb463ea1e6c686d0dc9638fc940f2f5cf17
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    8a3a2887794b2c8e78b3e5d6e3de724527c9f41b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    05f6e183879d9785a3cdf2f08a498bc31b7a20aa
  - Linux 2.6.12
published: '2025-07-04'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:06:49.281Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-38214'
references:
  - url: 'https://git.kernel.org/stable/c/ee20216f12d9482cd70e44dae5e7fabb38367c71'
  - url: 'https://git.kernel.org/stable/c/fab201d72fde38d081e2c5d4ad25595c535b7b22'
  - url: 'https://git.kernel.org/stable/c/1a10d91766eb6ddfd5414e4785611e33a4fe0f9b'
  - url: 'https://git.kernel.org/stable/c/ff0e037241173b574b385bff53d67567b9816db5'
  - url: 'https://git.kernel.org/stable/c/3ca78032a388a0795201792b36e6fc9b6e6e8eed'
  - url: 'https://git.kernel.org/stable/c/b3071bb463ea1e6c686d0dc9638fc940f2f5cf17'
  - url: 'https://git.kernel.org/stable/c/8a3a2887794b2c8e78b3e5d6e3de724527c9f41b'
  - url: 'https://git.kernel.org/stable/c/05f6e183879d9785a3cdf2f08a498bc31b7a20aa'
tags:
  - cve.org
epss: 0.00188
epssPercentile: 0.08362
ingestedAt: '2026-10-15T05:52:46.092Z'
---

## Overview

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

fbdev: Fix fb_set_var to prevent null-ptr-deref in fb_videomode_to_var

If fb_add_videomode() in fb_set_var() fails to allocate memory for
fb_videomode, later it may lead to a null-ptr dereference in
fb_videomode_to_var(), as the fb_info is registered while not having the
mode in modelist that is expected to be there, i.e. the one that is
described in fb_info->var.

================================================================
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 30371 Comm: syz-executor.1 Not tainted 5.10.226-syzkaller #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:fb_videomode_to_var+0x24/0x610 drivers/video/fbdev/core/modedb.c:901
Call Trace:
 display_to_var+0x3a/0x7c0 drivers/video/fbdev/core/fbcon.c:929
 fbcon_resize+0x3e2/0x8f0 drivers/video/fbdev/core/fbcon.c:2071
 resize_screen drivers/tty/vt/vt.c:1176 [inline]
 vc_do_resize+0x53a/0x1170 drivers/tty/vt/vt.c:1263
 fbcon_modechanged+0x3ac/0x6e0 drivers/video/fbdev/core/fbcon.c:2720
 fbcon_update_vcs+0x43/0x60 drivers/video/fbdev/core/fbcon.c:2776
 do_fb_ioctl+0x6d2/0x740 drivers/video/fbdev/core/fbmem.c:1128
 fb_ioctl+0xe7/0x150 drivers/video/fbdev/core/fbmem.c:1203
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:739
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x67/0xd1
================================================================

The reason is that fb_info->var is being modified in fb_set_var(), and
then fb_videomode_to_var() is called. If it fails to add the mode to
fb_info->modelist, fb_set_var() returns error, but does not restore the
old value of fb_info->var. Restore fb_info->var on failure the same way
it is done earlier in the function.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ee20216f12d9482cd70e44dae5e7fabb38367c71`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < fab201d72fde38d081e2c5d4ad25595c535b7b22`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1a10d91766eb6ddfd5414e4785611e33a4fe0f9b`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < ff0e037241173b574b385bff53d67567b9816db5`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3ca78032a388a0795201792b36e6fc9b6e6e8eed`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < b3071bb463ea1e6c686d0dc9638fc940f2f5cf17`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8a3a2887794b2c8e78b3e5d6e3de724527c9f41b`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 05f6e183879d9785a3cdf2f08a498bc31b7a20aa`
- `Linux 2.6.12`

## Remediation

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