214 lines
12 KiB
JSON
214 lines
12 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-74449",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-08-15T05:44:03.899Z",
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"datePublished": "2026-08-15T12:26:54.519Z",
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"dateUpdated": "2026-10-21T12:45:40.556Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-21T12:45:40.556Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport\n\nIf a plane reaches calculate_mcache_setting with a zero-area viewport,\ncalculate_mcache_setting exits early with num_mcaches == 0 and\nmvmpg_width/height == 0. This will cause a divide-by-zero panic and can\nalso cause an underflow on num_mcaches.\n\nFix this by changing calculate_mcache_setting to bool and adding guards\nafter each calculate_mcache_row_bytes call. If num_mcaches or\nmvmpg_width/height is zero, return a false. Callers will propagate the\nfailure as a rejected mode, which prevents the panic.\n\n(cherry picked from commit 29c0f7c655f47bcbd575ff75e58480df6ec3c9da)"
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:L - The bug is reached during DRM atomic display validation on AMDGPU DCN4.x (dml21 path): userspace ioctl → amdgpu_dm atomic commit → dc_validate_global_state/dc_validate_with_context → dcn401/dcn42_validate_bandwidth → dml2_validate → dml21_validate → dml2_check_mode_supported → dml2_core_calcs_mode_support_ex → calculate_mcache_setting; no network or physical bus is involved.\nAC:L - An attacker with DRM card access can submit atomic commits that configure DCC-enabled planes and repeatedly probe scaler/viewport edge cases (including degenerate zero-area viewports or zero mvmpg dimensions) to reach calculate_mcache_setting; once triggered, num_mcaches==0 deterministically underflows loop bounds and causes divide-by-zero without races or uncontrollable heap layout.\nPR:L - Exploitation requires only standard local DRM display privileges to perform atomic modeset ioctl on /dev/dri/card* (typical for session-owning desktop users in the video/render group), not init-namespace root/CAP_SYS_ADMIN; user namespaces do not grant independent access to the host GPU display stack.\nUI:N - No victim interaction is required beyond the attacker issuing their own DRM atomic commit to configure a plane with DCC compression enabled; the kernel panic/corruption occurs during in-kernel DML bandwidth validation, not from another user opening files or mounting filesystems.\nS:U - The vulnerability corrupts kernel memory and can enable local privilege escalation within the same host kernel running the AMDGPU display driver; it does not cross a VM, IOMMU, or sandbox boundary such as KVM guest-to-host escape.\nC:H - When num_mcaches is zero, unsigned underflow in loop bounds (n < *num_mcaches_l - 1) and indexing (mcache_offsets_l[*num_mcaches_l - 1]) performs massive out-of-bounds reads/writes past the fixed-size mcache_offsets arrays in kernel DML state, enabling disclosure of adjacent kernel heap memory rather than a pure crash with no data exposure.\nI:H - The same num_mcaches underflow drives unbounded out-of-bounds writes into mode_lib mcache offset arrays and related DML structures during calculate_mcache_setting, providing attacker-influenced kernel memory corruption primitives that could be leveraged for control-flow hijacking beyond a simple denial-of-service fault.\nA:H - The vulnerable path performs integer divide-by-zero on zero mvmpg_access_width/num_mcaches and executes out-of-bounds mcache offset writes, either of which can immediately trigger a kernel oops or panic during display mode validation, denying service to all users on affected AMD DCN4.x systems until reboot."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_core/dml2_core_dcn4_calcs.c"
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],
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"status": "affected",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/gpu/drm/amd/display/dc/dml2_0/dml21/src/dml2_core/dml2_core_dcn4_calcs.c"
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],
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"versions": [
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{
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"status": "affected"
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"version": "0",
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"lessThan": "6.11",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.114",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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},
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{
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"version": "6.18.57",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.1.8",
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"lessThanOrEqual": "7.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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"references": [
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"url": "https://git.kernel.org/stable/c/70f5f4ddba0d2d89e77ec13b79cdcfbef33be0d9"
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}
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],
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"title": "drm/amd/display: Fix divide-by-zero in calculate_mcache_setting on zero viewport",
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"id": "CVE-2026-74449",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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"Technical Impact": "total"
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"version": "2.0.3",
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"timestamp": "2026-10-16T18:56:48.300764Z"
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"title": "CISA ADP Vulnrichment",
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