CVE-2026-31488

/* * PoC for CVE-2026-31488 * Triggering the Use-After-Free in amdgpu DSC validation. * Compile: gcc -o poc cve-2026-31488.c -ldrm */ #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <drm/drm.h> #include <drm/drm_mode.h> int main() { int fd = open("/dev/dri/card0", O_RDWR | O_CLOEXEC); if (fd < 0) { perror("open"); return 1; } struct drm_mode_atomic atomic_arg = {0}; atomic_arg.flags = DRM_MODE_ATOMIC_TEST_ONLY | DRM_MODE_ATOMIC_ALLOW_MODESET; // Setup properties to trigger the specific path: // 1. Configure a CRTC with DSC enabled. // 2. Simulate a scenario where DSC config is recalculated but timing is same, // while another unrelated mode change is pending. // This requires specific hardware (AMD GPU) and topology. // In a real scenario, specific blob IDs and connector IDs are required. // This is a structural representation of the trigger. printf("Attempting to trigger atomic commit with conflicting mode state...\n"); // ioctl(fd, DRM_IOCTL_MODE_ATOMIC, &atomic_arg); close(fd); return 0; }

{"cve": {"id": "CVE-2026-31488", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:46.453", "lastModified": "2026-05-17T16:16:15.530", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amd/display: Do not skip unrelated mode changes in DSC validation\n\nStarting with commit 17ce8a6907f7 (\"drm/amd/display: Add dsc pre-validation in\natomic check\"), amdgpu resets the CRTC state mode_changed flag to false when\nrecomputing the DSC configuration results in no timing change for a particular\nstream.\n\nHowever, this is incorrect in scenarios where a change in MST/DSC configuration\nhappens in the same KMS commit as another (unrelated) mode change. For example,\nthe integrated panel of a laptop may be configured differently (e.g., HDR\nenabled/disabled) depending on whether external screens are attached. In this\ncase, plugging in external DP-MST screens may result in the mode_changed flag\nbeing dropped incorrectly for the integrated panel if its DSC configuration\ndid not change during precomputation in pre_validate_dsc().\n\nAt this point, however, dm_update_crtc_state() has already created new streams\nfor CRTCs with DSC-independent mode changes. In turn,\namdgpu_dm_commit_streams() will never release the old stream, resulting in a\nmemory leak. amdgpu_dm_atomic_commit_tail() will never acquire a reference to\nthe new stream either, which manifests as a use-after-free when the stream gets\ndisabled later on:\n\nBUG: KASAN: use-after-free in dc_stream_release+0x25/0x90 [amdgpu]\nWrite of size 4 at addr ffff88813d836524 by task kworker/9:9/29977\n\nWorkqueue: events drm_mode_rmfb_work_fn\nCall Trace:\n <TASK>\n dump_stack_lvl+0x6e/0xa0\n print_address_description.constprop.0+0x88/0x320\n ? dc_stream_release+0x25/0x90 [amdgpu]\n print_report+0xfc/0x1ff\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __virt_addr_valid+0x225/0x4e0\n ? dc_stream_release+0x25/0x90 [amdgpu]\n kasan_report+0xe1/0x180\n ? dc_stream_release+0x25/0x90 [amdgpu]\n kasan_check_range+0x125/0x200\n dc_stream_release+0x25/0x90 [amdgpu]\n dc_state_destruct+0x14d/0x5c0 [amdgpu]\n dc_state_release.part.0+0x4e/0x130 [amdgpu]\n dm_atomic_destroy_state+0x3f/0x70 [amdgpu]\n drm_atomic_state_default_clear+0x8ee/0xf30\n ? drm_mode_object_put.part.0+0xb1/0x130\n __drm_atomic_state_free+0x15c/0x2d0\n atomic_remove_fb+0x67e/0x980\n\nSince there is no reliable way of figuring out whether a CRTC has unrelated\nmode changes pending at the time of DSC validation, remember the value of the\nmode_changed flag from before the point where a CRTC was marked as potentially\naffected by a change in DSC configuration. Reset the mode_changed flag to this\nearlier value instead in pre_validate_dsc().\n\n(cherry picked from commit cc7c7121ae082b7b82891baa7280f1ff2608f22b)"}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.1", "versionEndExcluding": "6.12.80", "matchCriteriaId": "67222101-CC02-4250-A6E8-A98BDD29DB6F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.21", "matchCriteriaId": "ED39847A-3B46-4729-B7CA-B2C30B9FA8FE"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:5.18:-:*:*:*:*:*:*", "matchCriteriaId": "0384FA0A-DE99-48D7-84E3-46ED0C3B5E03"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": " ... 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