ghsa-fxqx-qp67-xrvv
Vulnerability from github
Published
2024-10-21 21:30
Modified
2024-10-24 00:33
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

In the Linux kernel, the following vulnerability has been resolved:

fbcon: Fix a NULL pointer dereference issue in fbcon_putcs

syzbot has found a NULL pointer dereference bug in fbcon. Here is the simplified C reproducer:

struct param { uint8_t type; struct tiocl_selection ts; };

int main() { struct fb_con2fbmap con2fb; struct param param;

int fd = open("/dev/fb1", 0, 0);

con2fb.console = 0x19;
con2fb.framebuffer = 0;
ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb);

param.type = 2;
param.ts.xs = 0; param.ts.ys = 0;
param.ts.xe = 0; param.ts.ye = 0;
param.ts.sel_mode = 0;

int fd1 = open("/dev/tty1", O_RDWR, 0);
ioctl(fd1, TIOCLINUX, &param);

con2fb.console = 1;
con2fb.framebuffer = 0;
ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb);

return 0;

}

After calling ioctl(fd1, TIOCLINUX, &param), the subsequent ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb) causes the kernel to follow a different execution path:

set_con2fb_map -> con2fb_init_display -> fbcon_set_disp -> redraw_screen -> hide_cursor -> clear_selection -> highlight -> invert_screen -> do_update_region -> fbcon_putcs -> ops->putcs

Since ops->putcs is a NULL pointer, this leads to a kernel panic. To prevent this, we need to call set_blitting_type() within set_con2fb_map() to properly initialize ops->putcs.

Show details on source website

To clipboard 

{
   affected: [],
   aliases: [
      "CVE-2024-50048",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-476",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-10-21T20:15:17Z",
      severity: "MODERATE",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nfbcon: Fix a NULL pointer dereference issue in fbcon_putcs\n\nsyzbot has found a NULL pointer dereference bug in fbcon.\nHere is the simplified C reproducer:\n\nstruct param {\n\tuint8_t type;\n\tstruct tiocl_selection ts;\n};\n\nint main()\n{\n\tstruct fb_con2fbmap con2fb;\n\tstruct param param;\n\n\tint fd = open(\"/dev/fb1\", 0, 0);\n\n\tcon2fb.console = 0x19;\n\tcon2fb.framebuffer = 0;\n\tioctl(fd, FBIOPUT_CON2FBMAP, &con2fb);\n\n\tparam.type = 2;\n\tparam.ts.xs = 0; param.ts.ys = 0;\n\tparam.ts.xe = 0; param.ts.ye = 0;\n\tparam.ts.sel_mode = 0;\n\n\tint fd1 = open(\"/dev/tty1\", O_RDWR, 0);\n\tioctl(fd1, TIOCLINUX, &param);\n\n\tcon2fb.console = 1;\n\tcon2fb.framebuffer = 0;\n\tioctl(fd, FBIOPUT_CON2FBMAP, &con2fb);\n\n\treturn 0;\n}\n\nAfter calling ioctl(fd1, TIOCLINUX, &param), the subsequent ioctl(fd, FBIOPUT_CON2FBMAP, &con2fb)\ncauses the kernel to follow a different execution path:\n\n set_con2fb_map\n  -> con2fb_init_display\n   -> fbcon_set_disp\n    -> redraw_screen\n     -> hide_cursor\n      -> clear_selection\n       -> highlight\n        -> invert_screen\n         -> do_update_region\n          -> fbcon_putcs\n           -> ops->putcs\n\nSince ops->putcs is a NULL pointer, this leads to a kernel panic.\nTo prevent this, we need to call set_blitting_type() within set_con2fb_map()\nto properly initialize ops->putcs.",
   id: "GHSA-fxqx-qp67-xrvv",
   modified: "2024-10-24T00:33:36Z",
   published: "2024-10-21T21:30:54Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-50048",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/5b97eebcce1b4f3f07a71f635d6aa3af96c236e7",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/8266ae6eafdcd5a3136592445ff4038bbc7ee80e",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/e5c2dba62996a3a6eeb34bd248b90fc69c5a6a1b",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/f7fb5dda555344529ce584ff7a28b109528d2f1b",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
         type: "CVSS_V3",
      },
   ],
}


Log in or create an account to share your comment.

Security Advisory comment format.

This schema specifies the format of a comment related to a security advisory.

UUIDv4 of the comment
UUIDv4 of the Vulnerability-Lookup instance
When the comment was created originally
When the comment was last updated
Title of the comment
Description of the comment
The identifier of the vulnerability (CVE ID, GHSA-ID, PYSEC ID, etc.).



Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.