CVE-2023-52872 tty: n_gsm: fix race condition in status line change on dead connections

2024-05-2115:32:06

Linux

github.com

linux kernel

race condition

n_gsm module

fix

status line change

dead connections

virtual tty

kernel panic

6.8 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.7%

JSON

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

tty: n_gsm: fix race condition in status line change on dead connections

gsm_cleanup_mux() cleans up the gsm by closing all DLCIs, stopping all
timers, removing the virtual tty devices and clearing the data queues.
This procedure, however, may cause subsequent changes of the virtual modem
status lines of a DLCI. More data is being added the outgoing data queue
and the deleted kick timer is restarted to handle this. At this point many
resources have already been removed by the cleanup procedure. Thus, a
kernel panic occurs.

Fix this by proving in gsm_modem_update() that the cleanup procedure has
not been started and the mux is still alive.

Note that writing to a virtual tty is already protected by checks against
the DLCI specific connection state.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/tty/n_gsm.c"
    ],
    "versions": [
      {
        "version": "dd37f6573878",
        "lessThan": "81a4dd5e6c78",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c568f7086c6e",
        "lessThan": "df6cfab66ff2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c568f7086c6e",
        "lessThan": "19d34b73234a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c568f7086c6e",
        "lessThan": "ce4df90333c4",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "c568f7086c6e",
        "lessThan": "3a75b205de43",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/tty/n_gsm.c"
    ],
    "versions": [
      {
        "version": "6.0",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.0",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.138",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.62",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.5.11",
        "lessThanOrEqual": "6.5.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.1",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]