CVE-2026-89803 (GCVE-0-2026-89803)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:30 – Updated: 2026-09-16 14:38
VLAI
Title
drm/nouveau: unsubscribe the channel-kill event before the fence context
Summary
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 its own, which is why this carries a Fixes: tag. The last patch in this series subscribes Tesla channels as well; nothing kills those today, so it does not widen the exposure now, but it is the groundwork for a recovery path that would, and the ordering is better fixed before that lands than alongside it. Drop the subscription before anything it depends on is torn down.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ea13e5abf807ea912ce84eef6a1946b9a38c6508 , < f5a79a9ebfbafb87ca7a896e8d6b5f33a98d097e (git)
Affected: ea13e5abf807ea912ce84eef6a1946b9a38c6508 , < f3830fdd6930e233d727f29eee1617f7e6a0e9e5 (git)
Affected: ea13e5abf807ea912ce84eef6a1946b9a38c6508 , < 1fef7553dc628295c1208a4f2ac2094c62886e5d (git)
Affected: ea13e5abf807ea912ce84eef6a1946b9a38c6508 , < 511585987d27d8cb668acebd399fc4deda23404c (git)
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Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc2 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/nouveau/nouveau_chan.c"
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          "vendor": "Linux",
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
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              "version": "7.2.5",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
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                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/nouveau: unsubscribe the channel-kill event before the fence context\n\nnouveau_channel_del() tears the fence context down first and only drops\nthe channel-kill subscription later, in the middle of the nvif object\nteardown:\n\n\tif (chan-\u003efence)\n\t\tnouveau_fence(chan-\u003ecli-\u003edrm)-\u003econtext_del(chan);\n\t...\n\tnvif_object_dtor(\u0026chan-\u003evram);\n\tnvif_event_dtor(\u0026chan-\u003ekill);\n\nThe subscribed handler is nouveau_channel_killed(), which calls\nnouveau_channel_kill() and from there nouveau_fence_context_kill() on\nchan-\u003efence. A kill event delivered in that window takes fctx-\u003elock and\nwalks fctx-\u003epending on a fence context that context_del() has already\nfreed.\n\nNothing reaches this below Fermi today, because the subscription is\ngated on FERMI_CHANNEL_GPFIFO and nothing kills a channel there. On\nFermi and newer the window is real but narrow, since a kill has to land\nexactly while the channel is being destroyed. That is reason enough on\nits own, which is why this carries a Fixes: tag. The last patch in this\nseries subscribes Tesla channels as well; nothing kills those today, so\nit does not widen the exposure now, but it is the groundwork for a\nrecovery path that would, and the ordering is better fixed before that\nlands than alongside it.\n\nDrop the subscription before anything it depends on is torn down."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
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            "version": "3.1"
          },
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              "value": "AV:L - Reached via local DRM ioctls DRM_IOCTL_NOUVEAU_CHANNEL_ALLOC/FREE on /dev/dri/renderD*, or by closing that fd (nouveau_drm_postclose\u2192nouveau_abi16_chan_fini\u2192nouveau_channel_del). Not reachable from network protocols, adjacent radios, or physical buses.\nAC:L - The attacker creates and destroys their own Fermi+ channel so the kill handler stays armed across fence teardown; they also induce the kill (illegal pushbuf/MMU fault or GSP RC during the still-subscribed nvif object dtors) and can retry, so they control both sides of the race.\nPR:L - CHANNEL_ALLOC and CHANNEL_FREE are DRM_RENDER_ALLOW with no ROOT_ONLY or capability checks. Any unprivileged local user who can open the nouveau render node (render/video group, logind ACL, Android GPU, or container) can trigger it.\nUI:N - The attacker opens their own nouveau render-node client and issues CHANNEL_ALLOC/FREE or close on that fd; no separate victim action is required.\nS:U - The use-after-free corrupts host kernel heap state (struct nouveau_fence_chan) inside the nouveau driver. Impact stays in the same kernel authority; this is not a VM escape or IOMMU/DMA isolation bypass.\nC:H - A channel-kill delivered after context_del uses chan-\u003efence on a freed fence context, taking fctx-\u003elock and walking fctx-\u003epending. Reclaiming that slab enables arbitrary kernel reads as with other UAFs.\nI:H - The same UAF lets the IRQ/GSP kill path list_del and dma_fence_signal through attacker-reclaimed fence-context and pending-list pointers, enabling heap corruption, arbitrary writes, and control-flow hijack.\nA:H - Dereferencing the freed fence context from nouveau_channel_killed() (spinlock/list walk in interrupt or GSP callback) oopses or panics the kernel; the attacker can repeat CHANNEL_FREE or close to crash the system."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-09-16T14:38:48.708Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        },
        {
          "url": "https://git.kernel.org/stable/c/511585987d27d8cb668acebd399fc4deda23404c"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89803",
    "datePublished": "2026-09-16T10:30:36.738Z",
    "dateReserved": "2026-09-11T19:38:34.767Z",
    "dateUpdated": "2026-09-16T14:38:48.708Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/nouveau: unsubscribe the channel-kill event before the fence context\n\nnouveau_channel_del() tears the fence context down first and only drops\nthe channel-kill subscription later, in the middle of the nvif object\nteardown:\n\n\tif (chan-\u003efence)\n\t\tnouveau_fence(chan-\u003ecli-\u003edrm)-\u003econtext_del(chan);\n\t...\n\tnvif_object_dtor(\u0026chan-\u003evram);\n\tnvif_event_dtor(\u0026chan-\u003ekill);\n\nThe subscribed handler is nouveau_channel_killed(), which calls\nnouveau_channel_kill() and from there nouveau_fence_context_kill() on\nchan-\u003efence. A kill event delivered in that window takes fctx-\u003elock and\nwalks fctx-\u003epending on a fence context that context_del() has already\nfreed.\n\nNothing reaches this below Fermi today, because the subscription is\ngated on FERMI_CHANNEL_GPFIFO and nothing kills a channel there. On\nFermi and newer the window is real but narrow, since a kill has to land\nexactly while the channel is being destroyed. That is reason enough on\nits own, which is why this carries a Fixes: tag. The last patch in this\nseries subscribes Tesla channels as well; nothing kills those today, so\nit does not widen the exposure now, but it is the groundwork for a\nrecovery path that would, and the ordering is better fixed before that\nlands than alongside it.\n\nDrop the subscription before anything it depends on is torn down."
          }
        ],
        "id": "CVE-2026-89803",
        "lastModified": "2026-09-16T15:18:09.993",
        "metrics": {
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              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-09-16T11:16:45.227",
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.