CVE-2026-89803

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

drm/nouveau: unsubscribe the channel-kill event before the fence context

nouveau_channel_del() tears the fence context down first and only drops

the channel-kill subscription later, in the middle of the nvif object

teardown:

if (chan->fence)

nouveau_fence(chan->cli->drm)->context_del(chan);

...

nvif_object_dtor(&chan->vram);

nvif_event_dtor(&chan->kill);

The subscribed handler is nouveau_channel_killed(), which calls

nouveau_channel_kill() and from there nouveau_fence_context_kill() on

chan->fence. A kill event delivered in that window takes fctx->lock and

walks fctx->pending on a fence context that context_del() has already

freed.

Nothing reaches this below Fermi today, because the subscription is

gated on FERMI_CHANNEL_GPFIFO and nothing kills a channel there. On

Fermi and newer the window is real but narrow, since a kill has to land

exactly while the channel is being destroyed. That is reason enough on

it

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References