{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-63884", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-63884" ], "published": "2026-07-19T14:56:29Z", "summary": "drm/i915: Fix potential UAF in TTM object purge", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/i915: Fix potential UAF in TTM object purge\n\nTLDR: The bo->ttm object might be changed by calling ttm_bo_validate(),\n move casting it to an i915_tt object later to actually get the right\n pointer.\n\nA user reported hitting the following bug under heavy use on DG2:\n\n[26620.095550] Oops: general protection fault, probably for non-canonical address 0xa56b6b6b6b6b6b8b: 0000 1 SMP NOPTI\n[26620.095556] CPU: 2 UID: 0 PID: 631 Comm: Xorg Not tainted 6.18.8 #1 PREEMPT(lazy)\n[26620.095558] Hardware name: ASRock B850M Steel Legend WiFi/B850M Steel Legend WiFi, BIOS 3.50 09/18/2025\n[26620.095559] RIP: 0010:i915_ttm_purge+0x84/0x100 [i915]\n[26620.095604] Code: 00 00 00 48 8d 54 24 10 48 89 e6 48 89 fb e8 83 aa ae ff 85 c0 75 6f 48 83 bb a8 01 00 00 00 74 2c 48 8b 45 78 48 85 c0 74 23 <48> 8b 78 20 48 c7 c2 ff ff ff ff 31 f6 e8 7a 73 e3 e0 48 8b 7d 78\n[26620.095605] RSP: 0018:ffffc90005fd7430 EFLAGS: 00010282\n[26620.095607] RAX: a56b6b6b6b6b6b6b RBX: ffff8881f46c3dc0 RCX: 0000000000000000\n[26620.095608] RDX: 0000000000000000 RSI: 0000000000000246 RDI: 00000000ffffffff\n[26620.095609] RBP: ffff888289610f00 R08: 0000000000000001 R09: ffff88823b022000\n[26620.095609] R10: ffff888103029b28 R11: ffff8881fc7f3800 R12: ffff88810b6150d0\n[26620.095609] R13: ffff888289610f00 R14: 0000000000000000 R15: ffff8881f46c3dc0\n[26620.095610] FS: 00007f1004d86900(0000) GS:ffff88901c858000(0000) knlGS:0000000000000000\n[26620.095611] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[26620.095611] CR2: 00007f0fdf489000 CR3: 000000035b0c1000 CR4: 0000000000750ef0\n[26620.095612] PKRU: 55555554\n[26620.095612] Call Trace:\n[26620.095615] \n[26620.095615] i915_ttm_move+0x2b9/0x420 [i915]\n[26620.095642] ? ttm_tt_init+0x65/0x80 [ttm]\n[26620.095644] ? i915_ttm_tt_create+0xc6/0x150 [i915]\n[26620.095667] ttm_bo_handle_move_mem+0xb6/0x160 [ttm]\n[26620.095669] ttm_bo_evict+0x100/0x150 [ttm]\n[26620.095671] ? preempt_count_add+0x64/0xa0\n[26620.095673] ? _raw_spin_lock+0xe/0x30\n[26620.095675] ? _raw_spin_unlock+0xd/0x30\n[26620.095675] ? i915_gem_object_evictable+0xb7/0xd0 [i915]\n[26620.095704] ttm_bo_evict_cb+0x6e/0xd0 [ttm]\n[26620.095705] ttm_lru_walk_for_evict+0xa6/0x200 [ttm]\n[26620.095708] ttm_bo_alloc_resource+0x185/0x4f0 [ttm]\n[26620.095709] ? init_object+0x62/0xd0\n[26620.095712] ttm_bo_validate+0x7a/0x180 [ttm]\n[26620.095713] ? _raw_spin_unlock_irqrestore+0x16/0x30\n[26620.095714] __i915_ttm_get_pages+0xb0/0x170 [i915]\n[26620.095737] i915_ttm_get_pages+0x9f/0x150 [i915]\n[26620.095759] ? i915_gem_do_execbuffer+0xedc/0x2b40 [i915]\n[26620.095786] ? alloc_debug_processing+0xd0/0x100\n[26620.095787] ? _raw_spin_unlock_irqrestore+0x16/0x30\n[26620.095788] ? i915_vma_instance+0xa0/0x4e0 [i915]\n[26620.095822] __i915_gem_object_get_pages+0x2f/0x40 [i915]\n[26620.095848] i915_vma_pin_ww+0x706/0x980 [i915]\n[26620.095875] ? i915_gem_do_execbuffer+0xedc/0x2b40 [i915]\n[26620.095904] eb_validate_vmas+0x170/0xa00 [i915]\n[26620.095930] i915_gem_do_execbuffer+0x1201/0x2b40 [i915]\n[26620.095953] ? alloc_debug_processing+0xd0/0x100\n[26620.095954] ? _raw_spin_unlock_irqrestore+0x16/0x30\n[26620.095955] ? i915_gem_execbuffer2_ioctl+0xc9/0x240 [i915]\n[26620.095977] ? __wake_up_sync_key+0x32/0x50\n[26620.095979] ? i915_gem_execbuffer2_ioctl+0xc9/0x240 [i915]\n[26620.096001] ? __slab_alloc.isra.0+0x67/0xc0\n[26620.096003] i915_gem_execbuffer2_ioctl+0x11a/0x240 [i915]\n\nResults from decode_stacktrace.sh pointed to dereference of a file pointer\nfield of a i915 TTM page vector container associated with an object being\npurged on eviction. That path is taken when the object is marked as no\nlonger needed.\n\nCode analysis revealed a possibility of the i915 TTM page vector container\nbeing replaced with a new instance inside a function that purges content\nof the object, should it be still busy. That function is called,\nindirectly via a more general function that changes the object's placement\nand caching policy,\n---truncated---", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.176", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-63884" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/df73f3bc731af1c39ac5405bc59c4e7c6f8e9117" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/28b22dbaf407598cb3bb1d2c586a6f8018690ac2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/073bcbc95e9648c976da1654c7590a8d6ee12c2d" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/c9ae7e7e3bc98615364313b08d7acea5239ded0b" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a29654d451bbffe63d584a4cf64ad0efce6bcf1c" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5c4063c87a619e4df954c179d24628636f5db15f" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T13:16:28Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The bug is reached only through local DRM ioctls on the Intel GPU render node (notably I915_GEM_EXECBUFFER2 and I915_GEM_MADVISE); there is no network, adjacent-radio, or physical-access entry path.\nAC:L - An attacker controls the triggering workload (concurrent execbuffers, madvise DONTNEED, and GPU memory pressure to force eviction), and the UAF is a deterministic stale-pointer bug rather than a race against uncontrollable system state.\nPR:L - Exploitation requires only access to the DRM render node and standard unprivileged GEM ioctls (DRM_RENDER_ALLOW); no CAP_SYS_ADMIN, DRM master, or init-namespace root is needed.\nUI:N - No victim interaction is required beyond the attacker (or a compromised local GPU client) issuing its own ioctl submissions to the render node.\nS:U - Successful exploitation yields kernel memory corruption and local privilege escalation within the same kernel security authority; it does not constitute a VM escape or IOMMU/DMA boundary bypass.\nC:H - This is a kernel heap use-after-free on a freed i915_ttm_tt structure; attacker-controlled reuse of the freed object can provide arbitrary kernel memory read primitives.\nI:H - UAF on the i915_ttm_tt/filp path enables heap grooming and corrupting kernel objects, providing a standard path to arbitrary kernel write and code execution.\nA:H - The vulnerability was observed causing a kernel general protection fault/oops under real workloads, and UAF in this path can reliably crash or hang the system even before full exploitation." } } }