gsd-2021-47085
Vulnerability from gsd
Modified
2024-03-01 06:04
Details
In the Linux kernel, the following vulnerability has been resolved: hamradio: improve the incomplete fix to avoid NPD The previous commit 3e0588c291d6 ("hamradio: defer ax25 kfree after unregister_netdev") reorder the kfree operations and unregister_netdev operation to prevent UAF. This commit improves the previous one by also deferring the nullify of the ax->tty pointer. Otherwise, a NULL pointer dereference bug occurs. Partial of the stack trace is shown below. BUG: kernel NULL pointer dereference, address: 0000000000000538 RIP: 0010:ax_xmit+0x1f9/0x400 ... Call Trace: dev_hard_start_xmit+0xec/0x320 sch_direct_xmit+0xea/0x240 __qdisc_run+0x166/0x5c0 __dev_queue_xmit+0x2c7/0xaf0 ax25_std_establish_data_link+0x59/0x60 ax25_connect+0x3a0/0x500 ? security_socket_connect+0x2b/0x40 __sys_connect+0x96/0xc0 ? __hrtimer_init+0xc0/0xc0 ? common_nsleep+0x2e/0x50 ? switch_fpu_return+0x139/0x1a0 __x64_sys_connect+0x11/0x20 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The crash point is shown as below static void ax_encaps(...) { ... set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); // ax->tty = NULL! ... } By placing the nullify action after the unregister_netdev, the ax->tty pointer won't be assigned as NULL net_device framework layer is well synchronized.
Aliases


To clipboard 

{
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2021-47085"
      ],
      "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhamradio: improve the incomplete fix to avoid NPD\n\nThe previous commit 3e0588c291d6 (\"hamradio: defer ax25 kfree after\nunregister_netdev\") reorder the kfree operations and unregister_netdev\noperation to prevent UAF.\n\nThis commit improves the previous one by also deferring the nullify of\nthe ax-\u003etty pointer. Otherwise, a NULL pointer dereference bug occurs.\nPartial of the stack trace is shown below.\n\nBUG: kernel NULL pointer dereference, address: 0000000000000538\nRIP: 0010:ax_xmit+0x1f9/0x400\n...\nCall Trace:\n dev_hard_start_xmit+0xec/0x320\n sch_direct_xmit+0xea/0x240\n __qdisc_run+0x166/0x5c0\n __dev_queue_xmit+0x2c7/0xaf0\n ax25_std_establish_data_link+0x59/0x60\n ax25_connect+0x3a0/0x500\n ? security_socket_connect+0x2b/0x40\n __sys_connect+0x96/0xc0\n ? __hrtimer_init+0xc0/0xc0\n ? common_nsleep+0x2e/0x50\n ? switch_fpu_return+0x139/0x1a0\n __x64_sys_connect+0x11/0x20\n do_syscall_64+0x33/0x40\n entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nThe crash point is shown as below\n\nstatic void ax_encaps(...) {\n  ...\n  set_bit(TTY_DO_WRITE_WAKEUP, \u0026ax-\u003etty-\u003eflags); // ax-\u003etty = NULL!\n  ...\n}\n\nBy placing the nullify action after the unregister_netdev, the ax-\u003etty\npointer won\u0027t be assigned as NULL net_device framework layer is well\nsynchronized.",
      "id": "GSD-2021-47085",
      "modified": "2024-03-01T06:04:48.334600Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cve@kernel.org",
        "ID": "CVE-2021-47085",
        "STATE": "REJECT"
      },
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "** REJECT ** This CVE ID has been rejected or withdrawn by its CVE Numbering Authority."
          }
        ]
      }
    },
    "nvd.nist.gov": {
      "cve": {
        "descriptions": [
          {
            "lang": "en",
            "value": "Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority."
          }
        ],
        "id": "CVE-2021-47085",
        "lastModified": "2024-03-19T14:15:07.603",
        "metrics": {},
        "published": "2024-03-04T18:15:07.317",
        "references": [],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Rejected"
      }
    }
  }
}


Log in or create an account to share your comment.




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.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • 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.