GHSA-H7HM-J4CR-JWHQ
Vulnerability from github – Published: 2024-05-21 15:31 – Updated: 2025-09-23 21:30In 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.
{
"affected": [],
"aliases": [
"CVE-2021-47383"
],
"database_specific": {
"cwe_ids": [
"CWE-125"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-21T15:15:23Z",
"severity": "HIGH"
},
"details": "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.",
"id": "GHSA-h7hm-j4cr-jwhq",
"modified": "2025-09-23T21:30:52Z",
"published": "2024-05-21T15:31:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47383"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7e71fcedfda6f7de18f850a6b36e78d78b04476f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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