138 lines
7.8 KiB
JSON
138 lines
7.8 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-2022-50221",
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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": "2025-06-18T10:57:27.430Z",
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"datePublished": "2025-06-18T11:03:56.096Z",
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"dateUpdated": "2026-08-05T08:57:46.137Z"
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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": "2026-08-05T08:57:46.137Z"
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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/fb-helper: Fix out-of-bounds access\n\nClip memory range to screen-buffer size to avoid out-of-bounds access\nin fbdev deferred I/O's damage handling.\n\nFbdev's deferred I/O can only track pages. From the range of pages, the\ndamage handler computes the clipping rectangle for the display update.\nIf the fbdev screen buffer ends near the beginning of a page, that page\ncould contain more scanlines. The damage handler would then track these\nnon-existing scanlines as dirty and provoke an out-of-bounds access\nduring the screen update. Hence, clip the maximum memory range to the\nsize of the screen buffer.\n\nWhile at it, rename the variables min/max to min_off/max_off in\ndrm_fb_helper_deferred_io(). This avoids confusion with the macros of\nthe same name."
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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 by opening /dev/fbN, mmap'ing the fbdev shadow buffer, and dirtying pages so fb_deferred_io_work calls drm_fb_helper_deferred_io(); that is a local device/syscall path with no network or adjacent-protocol entry.\nAC:L - On affected shadow-fbdev configurations whose screen_size is not page-aligned (common modes such as 1366x768x32), writing the last mapped page and flushing deferred I/O (or fsync) reliably enlarges the damage clip past the buffer; no race or attacker-uncontrollable layout is required.\nPR:L - fb_open() has no capability check; access is DAC on /dev/fbN (typically 660 root:video), which ordinary desktop, Android, and embedded graphics users hold via the video group—basic local privileges, not real root.\nUI:N - The attacker opens the framebuffer, mmaps it, and dirties the last page themselves; no separate victim action is required.\nS:U - Corruption stays in host kernel vmalloc/GEM memory under the same OS authority; this is not a VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - drm_fb_helper_damage_blit_real() reads past the vzalloc'd shadow buffer into adjacent kernel memory (often kilobytes for a full extra scanline), an out-of-bounds read well beyond a few bytes that can disclose neighboring contents into the blit/display path.\nI:H - The same oversized clip drives iosys_map_memcpy_to() past the logical framebuffer into memory beyond the page-aligned GEM allocation (e.g. ~3KB past the BO for 1366x768x32), a kernel out-of-bounds write exploitable for heap corruption/control-flow impact.\nA:H - Accesses past the shadow/GEM allocations into unmapped vmalloc/guard regions can oops or panic the kernel, so availability impact is High."
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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/drm_fb_helper.c"
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],
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"versions": [
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{
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"version": "67b723f5b74254d27962b1b59bddfee1584575ff",
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"lessThan": "9c49ac792c639dbec0728b513329a32461f72253",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "67b723f5b74254d27962b1b59bddfee1584575ff",
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"lessThan": "ae25885bdf59fde40726863c57fd20e4a0642183",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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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/drm_fb_helper.c"
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],
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"versions": [
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{
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"version": "5.18",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "5.18",
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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": "5.19.2",
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"lessThanOrEqual": "5.19.*",
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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": "6.0",
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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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],
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"cpeApplicability": [
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.18",
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"versionEndExcluding": "5.19.2"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.18",
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"versionEndExcluding": "6.0"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/9c49ac792c639dbec0728b513329a32461f72253"
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},
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{
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"url": "https://git.kernel.org/stable/c/ae25885bdf59fde40726863c57fd20e4a0642183"
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}
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],
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"title": "drm/fb-helper: Fix out-of-bounds access",
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"x_generator": {
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