CVE-2026-89815 (GCVE-0-2026-89815)
Vulnerability from cvelistv5
Published
2026-09-16 10:30
Modified
2026-10-19 08:53
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/ttm: Drop tt->restore after successful restore ttm_pool_restore_and_alloc() can successfully complete the restore process via ttm_pool_restore_commit(), but tt->restore is not dropped afterward. As a result, subsequent backup/restore flows observe what appears to be a completed restore, while in reality shmem handles are still installed in tt->pages, leading to the stack trace below. Fix this by freeing and dropping tt->restore in ttm_pool_restore_and_alloc() upon successful completion of the restore. 20545 [  309.784531] RIP: 0010:sg_alloc_append_table_from_pages+0x38c/0x490 20547 [  309.809570] RSP: 0018:ffffc9000623b838 EFLAGS: 00010206 20548 [  309.814827] RAX: 0000000000001000 RBX: ffff88816e42a160 RCX: 0000000000000000 20549 [  309.821986] RDX: 0000000000002000 RSI: 0000000000000003 RDI: 0000000000001000 20550 [  309.829147] RBP: ffff88816e42a168 R08: 0000000000000002 R09: 000000007ffff000 20551 [  309.836310] R10: ffffc9000623b928 R11: 0000000000000000 R12: 000000007ffff000 20552 [  309.843471] R13: ffff88815ba5a100 R14: 0000000000000000 R15: 0000000000000001 20553 [  309.850634] FS:  00007f9ff305e700(0000) GS:ffff888276c94000(0000) knlGS:0000000000000000 20554 [  309.858749] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 20555 [  309.864519] CR2: 00007f9fca701000 CR3: 00000001565e2005 CR4: 0000000008f70ef0 20556 [  309.871678] PKRU: 55555558 20557 [  309.874403] Call Trace: 20558 [  309.876866]  <TASK> 20559 [  309.878988]  sg_alloc_table_from_pages_segment+0x60/0x100 20560 [  309.884415]  ? ttm_resource_manager_usage+0x36/0x60 [ttm] 20561 [  309.889845]  ? xe_tt_map_sg+0x7d/0xd0 [xe] 20562 [  309.894045]  xe_tt_map_sg+0x7d/0xd0 [xe] 20563 [  309.898037]  xe_bo_move+0x927/0xaa0 [xe] 20564 [  309.902029]  ttm_bo_handle_move_mem+0xba/0x170 [ttm] 20565 [  309.907022]  ttm_bo_validate+0xbe/0x190 [ttm] 20566 [  309.911405]  xe_bo_validate+0x9a/0x120 [xe] 20567 [  309.915663]  xe_gpuvm_validate+0xd9/0x140 [xe] 20568 [  309.920206]  drm_gpuvm_validate+0x2f0/0x5b0 [drm_gpuvm] 20569 [  309.925459]  ? drm_exec_lock_obj+0x63/0x210 [drm_exec] 20570 [  309.930627]  xe_vm_validate_rebind+0x46/0xb0 [xe] 20571 [  309.935428]  xe_exec_fn+0x20/0x40 [xe] 20572 [  309.939249]  drm_gpuvm_exec_lock+0x78/0xc0 [drm_gpuvm] 20573 [  309.944410]  xe_validation_exec_lock+0x5a/0xa0 [xe] 20574 [  309.949385]  xe_exec_ioctl+0x806/0xc30 [xe] 20575 [  309.953639]  ? ttwu_queue_wakelist+0xd9/0xf0 20576 [  309.957935]  ? __pfx_xe_exec_fn+0x10/0x10 [xe] 20577 [  309.962449]  ? __wake_up_common+0x73/0xa0 20578 [  309.966482]  ? __pfx_xe_exec_ioctl+0x10/0x10 [xe] 20579 [  309.971263]  drm_ioctl_kernel+0xa3/0x100 20580 [  309.975209]  drm_ioctl+0x213/0x440 20581 [  309.978637]  ? __pfx_xe_exec_ioctl+0x10/0x10 [xe] 20582 [  309.983415]  xe_drm_ioctl+0x67/0xd0 [xe] 20583 [  309.987408]  __x64_sys_ioctl+0x7f/0xd0
References
Impacted products
Vendor Product Version
Linux Linux Version: b63d715b8090aed48bdef5930625946fa4c0d324
Version: b63d715b8090aed48bdef5930625946fa4c0d324
Version: b63d715b8090aed48bdef5930625946fa4c0d324
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/ttm/ttm_pool.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "329ddc5d438f991f49e4fd24c704d1c7288d5e03",
              "status": "affected",
              "version": "b63d715b8090aed48bdef5930625946fa4c0d324",
              "versionType": "git"
            },
            {
              "lessThan": "a46ab76b6cf5478e2ac7b942a377c7a1827b436a",
              "status": "affected",
              "version": "b63d715b8090aed48bdef5930625946fa4c0d324",
              "versionType": "git"
            },
            {
              "lessThan": "941ac10529b3be5965a88d432a161ab459672ba8",
              "status": "affected",
              "version": "b63d715b8090aed48bdef5930625946fa4c0d324",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/ttm/ttm_pool.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/ttm: Drop tt-\u003erestore after successful restore\n\nttm_pool_restore_and_alloc() can successfully complete the restore\nprocess via ttm_pool_restore_commit(), but tt-\u003erestore is not dropped\nafterward. As a result, subsequent backup/restore flows observe what\nappears to be a completed restore, while in reality shmem handles are\nstill installed in tt-\u003epages, leading to the stack trace below.\n\nFix this by freeing and dropping tt-\u003erestore in\nttm_pool_restore_and_alloc() upon successful completion of the restore.\n\n20545 [\u00a0 309.784531] RIP: 0010:sg_alloc_append_table_from_pages+0x38c/0x490\n20547 [\u00a0 309.809570] RSP: 0018:ffffc9000623b838 EFLAGS: 00010206\n20548 [\u00a0 309.814827] RAX: 0000000000001000 RBX: ffff88816e42a160 RCX: 0000000000000000\n20549 [\u00a0 309.821986] RDX: 0000000000002000 RSI: 0000000000000003 RDI: 0000000000001000\n20550 [\u00a0 309.829147] RBP: ffff88816e42a168 R08: 0000000000000002 R09: 000000007ffff000\n20551 [\u00a0 309.836310] R10: ffffc9000623b928 R11: 0000000000000000 R12: 000000007ffff000\n20552 [\u00a0 309.843471] R13: ffff88815ba5a100 R14: 0000000000000000 R15: 0000000000000001\n20553 [\u00a0 309.850634] FS:\u00a0 00007f9ff305e700(0000) GS:ffff888276c94000(0000) knlGS:0000000000000000\n20554 [\u00a0 309.858749] CS:\u00a0 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n20555 [\u00a0 309.864519] CR2: 00007f9fca701000 CR3: 00000001565e2005 CR4: 0000000008f70ef0\n20556 [\u00a0 309.871678] PKRU: 55555558\n20557 [\u00a0 309.874403] Call Trace:\n20558 [\u00a0 309.876866]\u00a0 \u003cTASK\u003e\n20559 [\u00a0 309.878988]\u00a0 sg_alloc_table_from_pages_segment+0x60/0x100\n20560 [\u00a0 309.884415]\u00a0 ? ttm_resource_manager_usage+0x36/0x60 [ttm]\n20561 [\u00a0 309.889845]\u00a0 ? xe_tt_map_sg+0x7d/0xd0 [xe]\n20562 [\u00a0 309.894045]\u00a0 xe_tt_map_sg+0x7d/0xd0 [xe]\n20563 [\u00a0 309.898037]\u00a0 xe_bo_move+0x927/0xaa0 [xe]\n20564 [\u00a0 309.902029]\u00a0 ttm_bo_handle_move_mem+0xba/0x170 [ttm]\n20565 [\u00a0 309.907022]\u00a0 ttm_bo_validate+0xbe/0x190 [ttm]\n20566 [\u00a0 309.911405]\u00a0 xe_bo_validate+0x9a/0x120 [xe]\n20567 [\u00a0 309.915663]\u00a0 xe_gpuvm_validate+0xd9/0x140 [xe]\n20568 [\u00a0 309.920206]\u00a0 drm_gpuvm_validate+0x2f0/0x5b0 [drm_gpuvm]\n20569 [\u00a0 309.925459]\u00a0 ? drm_exec_lock_obj+0x63/0x210 [drm_exec]\n20570 [\u00a0 309.930627]\u00a0 xe_vm_validate_rebind+0x46/0xb0 [xe]\n20571 [\u00a0 309.935428]\u00a0 xe_exec_fn+0x20/0x40 [xe]\n20572 [\u00a0 309.939249]\u00a0 drm_gpuvm_exec_lock+0x78/0xc0 [drm_gpuvm]\n20573 [\u00a0 309.944410]\u00a0 xe_validation_exec_lock+0x5a/0xa0 [xe]\n20574 [\u00a0 309.949385]\u00a0 xe_exec_ioctl+0x806/0xc30 [xe]\n20575 [\u00a0 309.953639]\u00a0 ? ttwu_queue_wakelist+0xd9/0xf0\n20576 [\u00a0 309.957935]\u00a0 ? __pfx_xe_exec_fn+0x10/0x10 [xe]\n20577 [\u00a0 309.962449]\u00a0 ? __wake_up_common+0x73/0xa0\n20578 [\u00a0 309.966482]\u00a0 ? __pfx_xe_exec_ioctl+0x10/0x10 [xe]\n20579 [\u00a0 309.971263]\u00a0 drm_ioctl_kernel+0xa3/0x100\n20580 [\u00a0 309.975209]\u00a0 drm_ioctl+0x213/0x440\n20581 [\u00a0 309.978637]\u00a0 ? __pfx_xe_exec_ioctl+0x10/0x10 [xe]\n20582 [\u00a0 309.983415]\u00a0 xe_drm_ioctl+0x67/0xd0 [xe]\n20583 [\u00a0 309.987408]\u00a0 __x64_sys_ioctl+0x7f/0xd0"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached only via local DRM ioctls on a TTM GPU (Intel Xe xe_exec_ioctl -\u003e xe_bo_validate -\u003e ttm_bo_validate -\u003e ttm_tt_restore -\u003e ttm_pool_restore_and_alloc). It is not reachable from network packets, Bluetooth/Wi-Fi frames, or USB.\nAC:L - An attacker can create shrinkable GPU BOs, induce reclaim so the Xe shrinker backs them up to shmem, then retry exec/validate to resume restore and later backup/restore again. Both sides of the backup/restore sequence are attacker-driven and retryable; no victim-only timing or rare non-default config is required.\nPR:L - xe_exec_ioctl, GEM create, and VM bind are DRM_RENDER_ALLOW with no CAP_SYS_ADMIN or DRM-master check. An unprivileged local user with typical render/video-group access to /dev/dri/renderD* on Xe systems can open the render node and exercise this path.\nUI:N - The attacker opens the render node, creates BOs, and issues exec/validate ioctls in their own process. No separate victim action such as mounting a filesystem or opening a file is required.\nS:U - Impact stays in the host kernel TTM/DRM authority (bogus page pointers used for SG/DMA and page-fault mapping). This is not a guest-to-host, IOMMU, or sandbox boundary escape.\nC:H - After a successful resumed restore, tt-\u003erestore is left set so a later backup/restore skips restore while shmem handles remain in tt-\u003epages. Those handles are type-confused as struct page * in sg_alloc_append_table_from_pages, dma_map_sgtable, and ttm_bo_vm_fault page_to_pfn/vmf_insert_pfn, which can disclose kernel or physical memory.\nI:H - The same page-pointer type confusion feeds encoded shmem handles into scatter-gather DMA mapping and vmf_insert_pfn, which is memory corruption exploitable for arbitrary write or control-flow hijack rather than a pure crash.\nA:H - The reported oops is a kernel crash in sg_alloc_append_table_from_pages while walking the still-encoded handles as page pointers, which takes down the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:53:09.454Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/329ddc5d438f991f49e4fd24c704d1c7288d5e03"
        },
        {
          "url": "https://git.kernel.org/stable/c/a46ab76b6cf5478e2ac7b942a377c7a1827b436a"
        },
        {
          "url": "https://git.kernel.org/stable/c/941ac10529b3be5965a88d432a161ab459672ba8"
        }
      ],
      "title": "drm/ttm: Drop tt-\u003erestore after successful restore",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89815",
    "datePublished": "2026-09-16T10:30:48.133Z",
    "dateReserved": "2026-09-11T19:38:34.768Z",
    "dateUpdated": "2026-10-19T08:53:09.454Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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