CVE-2025-38214
Medium · 5.5CVSS
5.5
EPSS
0.2%
Published
Jul 4, 2025
CISA due date
—
Cloudanix analysis
A flaw in the Linux kernel's display handling code can cause the system to crash when certain memory operations fail, and fixing it requires updating the kernel or related packages.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Memory Corruption
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Null pointer dereference in fb_videomode_to_var when fb_set_var fails to allocate memory for a videomode, leaving fb_info unregistered with the expected mode in its modelist while fb_info->var has already been modified without restoration on error.
Why it matters to the business
Local denial of service via kernel panic or crash on systems using the fbdev subsystem, increasing operational downtime risk for affected Linux deployments; low exploitability reduces urgency but still requires patching to maintain stability.
How an attack unfolds
An attacker with local access invokes fb_set_var through ioctls or console operations, forcing a memory allocation failure in fb_add_videomode; this leaves the framebuffer state inconsistent so that subsequent calls to fb_videomode_to_var during resize or mode change dereference a null pointer.
How to fix it
Update the Linux kernel to a version containing commit ee20216f12d9482cd70e44dae5e7fabb38367c71 or later; for verticadb-operator packages upgrade to 25.2.1.0-r1 or newer on Chainguard and Wolfi distributions.
How to confirm the fix worked
Confirm the running kernel contains the fix commit or is newer than the vulnerable version; exercise fb_set_var paths under memory pressure and verify no null dereference occurs and old var state is restored on allocation failure.
Typical attack path
- Obtain local user access on a vulnerable Linux system
- Trigger framebuffer ioctls or console resize operations that call fb_set_var
- Force memory allocation failure inside fb_add_videomode
- Cause fb_videomode_to_var to dereference a null pointer leading to crash
How to detect it
Review kernel logs for general protection faults or KASAN null-ptr-deref reports referencing fb_videomode_to_var, fb_set_var, or fbcon_resize; correlate with processes issuing fb ioctls or console resize activity.
What your security team should do
- Prioritize kernel upgrades on systems exposing framebuffer or console interfaces
- Monitor EPSS trend and re-evaluate if local exploit code appears
- Apply the specific fixed versions listed for affected packages
- Test framebuffer-related workloads after patching to confirm stability
The record
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 packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Debian:11 | linux | 0 | No fix |
| Debian:12 | linux | 0 | No fix |
| Debian:13 | linux | 0 | No fix |
| Debian:14 | linux | 0 | 6.12.35-1 |
| Linux | Kernel | 2.6.12 | 5.4.295 |
| Mageia:9 | kernel | 0 | 6.6.101-1.mga9 |
| Mageia:9 | kernel-linus | 0 | 6.6.101-1.mga9 |
| Mageia:9 | kmod-virtualbox | 0 | 7.1.10-7.mga9 |
| Mageia:9 | kmod-xtables-addons | 0 | 3.24-83.mga9 |
| Mageia:9 | wireless-regdb | 0 | 20250710-1.mga9 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6-RT_Update_14 | 0 | 1-150600.1.5.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_14 | 0 | 1-150600.13.3.4 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_3 | 0 | 1-150700.1.5.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-64kb | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.65.1.150600.12.28.4 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-coco | 0 | 6.4.0-15061.28.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-coco_debug | 0 | 6.4.0-15061.28.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-source-coco | 0 | 6.4.0-15061.28.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-syms-coco | 0 | 6.4.0-15061.28.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-azure | 0 | 6.4.0-150600.8.48.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | 0 | 6.4.0-150600.8.48.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-syms-azure | 0 | 6.4.0-150600.8.48.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt | 0 | 6.4.0-150600.10.49.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt_debug | 0 | 6.4.0-150600.10.49.1 |
| SUSE:Real Time Module 15 SP6 | kernel-source-rt | 0 | 6.4.0-150600.10.49.1 |
| SUSE:Real Time Module 15 SP6 | kernel-syms-rt | 0 | 6.4.0-150600.10.49.1 |
| SUSE:Real Time Module 15 SP7 | kernel-rt | 0 | 6.4.0-150700.7.13.1 |
| SUSE:Real Time Module 15 SP7 | kernel-source-rt | 0 | 6.4.0-150700.7.13.1 |
| SUSE:Real Time Module 15 SP7 | kernel-syms-rt | 0 | 6.4.0-150700.7.13.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-azure | 0 | 6.4.0-150600.8.48.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.65.1.150600.12.28.4 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-rt | 0 | 6.4.0-150600.10.49.1 |
| openSUSE:Leap 15.6 | kernel-rt_debug | 0 | 6.4.0-150600.10.49.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-source-azure | 0 | 6.4.0-150600.8.48.1 |
| openSUSE:Leap 15.6 | kernel-source-rt | 0 | 6.4.0-150600.10.49.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 15.6 | kernel-syms-azure | 0 | 6.4.0-150600.8.48.1 |
| openSUSE:Leap 15.6 | kernel-syms-rt | 0 | 6.4.0-150600.10.49.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.65.1 |
| openSUSE:Leap 16.0 | dtb-aarch64 | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-64kb | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default-base | 0 | 6.12.0-160000.6.1.160000.2.4 |
| openSUSE:Leap 16.0 | kernel-docs | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-rt | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-source | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-syms | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | 0 | 6.12.0-160000.6.1 |
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