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CVE-2026-63942

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: parport: Fix race between port and client registration The parport subsystem registers port devices before they are fully initialised, resulting in a race condition where client drivers such as lp can attach to ports that are not completely initialised or even being torn down. When the port and client drivers are built as modules and loaded around the same time during boot, this occasionally results in a crash. I was able to make this happen reliably in a VM with a PC-style parallel port by patching parport_pc to fail probing: > --- a/drivers/parport/parport_pc.c > +++ b/drivers/parport/parport_pc.c > @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base, > if (!p) > goto out3; > > - base_res = request_region(base, 3, p->name); > + base_res = NULL; > if (!base_res) > goto out4; > and then running: while true; do modprobe lp & modprobe parport_pc wait rmmod lp parport_pc done for a few seconds. In the long term I think port registration should be changed to put the call to device_add() inside parport_announce_port(), but since the latter currently cannot fail this will require changing all port drivers. For now, add a flag to indicate whether a port has been "announced" and only try to attach client drivers to ports when the flag is set.

Severity
HIGH
CVSS score
7.8 (v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-19 16:17:12.747000
Last modified
2026-10-26 13:35:00.073000
View original CVE JSON 
{
  "id": "CVE-2026-63942",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-07-19T16:17:12.747",
  "lastModified": "2026-10-26T13:35:00.073",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nparport: Fix race between port and client registration\n\nThe parport subsystem registers port devices before they are fully\ninitialised, resulting in a race condition where client drivers such\nas lp can attach to ports that are not completely initialised or even\nbeing torn down.\n\nWhen the port and client drivers are built as modules and loaded\naround the same time during boot, this occasionally results in a\ncrash.  I was able to make this happen reliably in a VM with a\nPC-style parallel port by patching parport_pc to fail probing:\n\n> --- a/drivers/parport/parport_pc.c\n> +++ b/drivers/parport/parport_pc.c\n> @@ -2069,7 +2069,7 @@ static struct parport *__parport_pc_probe_port(unsigned long int base,\n>  \tif (!p)\n>  \t\tgoto out3;\n>\n> -\tbase_res = request_region(base, 3, p->name);\n> +\tbase_res = NULL;\n>  \tif (!base_res)\n>  \t\tgoto out4;\n>\n\nand then running:\n\n    while true; do\n        modprobe lp & modprobe parport_pc\n\twait\n\trmmod lp parport_pc\n    done\n\nfor a few seconds.\n\nIn the long term I think port registration should be changed to put\nthe call to device_add() inside parport_announce_port(), but since the\nlatter currently cannot fail this will require changing all port\ndrivers.\n\nFor now, add a flag to indicate whether a port has been \"announced\"\nand only try to attach client drivers to ports when the flag is set."
    }
  ],
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          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
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