fkie_cve-2021-47383
Vulnerability from fkie_nvd
Published
2024-05-21 15:15
Modified
2025-09-23 20:14
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tty: Fix out-of-bound vmalloc access in imageblit This issue happens when a userspace program does an ioctl FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct containing only the fields xres, yres, and bits_per_pixel with values. If this struct is the same as the previous ioctl, the vc_resize() detects it and doesn't call the resize_screen(), leaving the fb_var_screeninfo incomplete. And this leads to the updatescrollmode() calculates a wrong value to fbcon_display->vrows, which makes the real_y() return a wrong value of y, and that value, eventually, causes the imageblit to access an out-of-bound address value. To solve this issue I made the resize_screen() be called even if the screen does not need any resizing, so it will "fix and fill" the fb_var_screeninfo independently.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982cPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7e71fcedfda6f7de18f850a6b36e78d78b04476fPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982cPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557bPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8bPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/7e71fcedfda6f7de18f850a6b36e78d78b04476fPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002aPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

{
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: Fix out-of-bound vmalloc access in imageblit\n\nThis issue happens when a userspace program does an ioctl\nFBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct\ncontaining only the fields xres, yres, and bits_per_pixel\nwith values.\n\nIf this struct is the same as the previous ioctl, the\nvc_resize() detects it and doesn\u0027t call the resize_screen(),\nleaving the fb_var_screeninfo incomplete. And this leads to\nthe updatescrollmode() calculates a wrong value to\nfbcon_display-\u003evrows, which makes the real_y() return a\nwrong value of y, and that value, eventually, causes\nthe imageblit to access an out-of-bound address value.\n\nTo solve this issue I made the resize_screen() be called\neven if the screen does not need any resizing, so it will\n\"fix and fill\" the fb_var_screeninfo independently."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: tty: corrige el acceso vmalloc fuera de los l\u00edmites en imageblit. Este problema ocurre cuando un programa de espacio de usuario realiza un ioctl FBIOPUT_VSCREENINFO pasando la estructura fb_var_screeninfo que contiene solo los campos xres, yres y bits_per_pixel con valores. Si esta estructura es la misma que la ioctl anterior, vc_resize() la detecta y no llama a resize_screen(), dejando fb_var_screeninfo incompleto. Y esto lleva a que updatecrollmode() calcule un valor incorrecto para fbcon_display-\u0026gt;vrows, lo que hace que real_y() devuelva un valor incorrecto de y, y ese valor, eventualmente, hace que imageblit acceda a un valor de direcci\u00f3n fuera de los l\u00edmites. . Para resolver este problema, hice que se llamara a resize_screen() incluso si la pantalla no necesita ning\u00fan cambio de tama\u00f1o, por lo que \"arreglar\u00e1 y completar\u00e1\" fb_var_screeninfo de forma independiente."
    }
  ],
  "id": "CVE-2021-47383",
  "lastModified": "2025-09-23T20:14:35.603",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
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        "exploitabilityScore": 1.8,
        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
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  "published": "2024-05-21T15:15:23.873",
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}


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