GSD-2024-26737

Vulnerability from gsd - Updated: 2024-02-20 06:02
Details
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel The following race is possible between bpf_timer_cancel_and_free and bpf_timer_cancel. It will lead a UAF on the timer->timer. bpf_timer_cancel(); spin_lock(); t = timer->time; spin_unlock(); bpf_timer_cancel_and_free(); spin_lock(); t = timer->timer; timer->timer = NULL; spin_unlock(); hrtimer_cancel(&t->timer); kfree(t); /* UAF on t */ hrtimer_cancel(&t->timer); In bpf_timer_cancel_and_free, this patch frees the timer->timer after a rcu grace period. This requires a rcu_head addition to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init, this does not need a kfree_rcu because it is still under the spin_lock and timer->timer has not been visible by others yet. In bpf_timer_cancel, rcu_read_lock() is added because this helper can be used in a non rcu critical section context (e.g. from a sleepable bpf prog). Other timer->timer usages in helpers.c have been audited, bpf_timer_cancel() is the only place where timer->timer is used outside of the spin_lock. Another solution considered is to mark a t->flag in bpf_timer_cancel and clear it after hrtimer_cancel() is done. In bpf_timer_cancel_and_free, it busy waits for the flag to be cleared before kfree(t). This patch goes with a straight forward solution and frees timer->timer after a rcu grace period.
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{
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2024-26737"
      ],
      "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel\n\nThe following race is possible between bpf_timer_cancel_and_free\nand bpf_timer_cancel. It will lead a UAF on the timer-\u003etimer.\n\nbpf_timer_cancel();\n\tspin_lock();\n\tt = timer-\u003etime;\n\tspin_unlock();\n\n\t\t\t\t\tbpf_timer_cancel_and_free();\n\t\t\t\t\t\tspin_lock();\n\t\t\t\t\t\tt = timer-\u003etimer;\n\t\t\t\t\t\ttimer-\u003etimer = NULL;\n\t\t\t\t\t\tspin_unlock();\n\t\t\t\t\t\thrtimer_cancel(\u0026t-\u003etimer);\n\t\t\t\t\t\tkfree(t);\n\n\t/* UAF on t */\n\thrtimer_cancel(\u0026t-\u003etimer);\n\nIn bpf_timer_cancel_and_free, this patch frees the timer-\u003etimer\nafter a rcu grace period. This requires a rcu_head addition\nto the \"struct bpf_hrtimer\". Another kfree(t) happens in bpf_timer_init,\nthis does not need a kfree_rcu because it is still under the\nspin_lock and timer-\u003etimer has not been visible by others yet.\n\nIn bpf_timer_cancel, rcu_read_lock() is added because this helper\ncan be used in a non rcu critical section context (e.g. from\na sleepable bpf prog). Other timer-\u003etimer usages in helpers.c\nhave been audited, bpf_timer_cancel() is the only place where\ntimer-\u003etimer is used outside of the spin_lock.\n\nAnother solution considered is to mark a t-\u003eflag in bpf_timer_cancel\nand clear it after hrtimer_cancel() is done.  In bpf_timer_cancel_and_free,\nit busy waits for the flag to be cleared before kfree(t). This patch\ngoes with a straight forward solution and frees timer-\u003etimer after\na rcu grace period.",
      "id": "GSD-2024-26737",
      "modified": "2024-02-20T06:02:29.189474Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cve@kernel.org",
        "ID": "CVE-2024-26737",
        "STATE": "PUBLIC"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "Linux",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c",
                          "version_name": "b00628b1c7d5",
                          "version_value": "5268bb02107b"
                        },
                        {
                          "version_value": "not down converted",
                          "x_cve_json_5_version_data": {
                            "defaultStatus": "affected",
                            "versions": [
                              {
                                "status": "affected",
                                "version": "5.15"
                              },
                              {
                                "lessThan": "5.15",
                                "status": "unaffected",
                                "version": "0",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.15.*",
                                "status": "unaffected",
                                "version": "5.15.150",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "6.1.*",
                                "status": "unaffected",
                                "version": "6.1.80",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "6.6.*",
                                "status": "unaffected",
                                "version": "6.6.19",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "6.7.*",
                                "status": "unaffected",
                                "version": "6.7.7",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "*",
                                "status": "unaffected",
                                "version": "6.8",
                                "versionType": "original_commit_for_fix"
                              }
                            ]
                          }
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "Linux"
            }
          ]
        }
      },
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel\n\nThe following race is possible between bpf_timer_cancel_and_free\nand bpf_timer_cancel. It will lead a UAF on the timer-\u003etimer.\n\nbpf_timer_cancel();\n\tspin_lock();\n\tt = timer-\u003etime;\n\tspin_unlock();\n\n\t\t\t\t\tbpf_timer_cancel_and_free();\n\t\t\t\t\t\tspin_lock();\n\t\t\t\t\t\tt = timer-\u003etimer;\n\t\t\t\t\t\ttimer-\u003etimer = NULL;\n\t\t\t\t\t\tspin_unlock();\n\t\t\t\t\t\thrtimer_cancel(\u0026t-\u003etimer);\n\t\t\t\t\t\tkfree(t);\n\n\t/* UAF on t */\n\thrtimer_cancel(\u0026t-\u003etimer);\n\nIn bpf_timer_cancel_and_free, this patch frees the timer-\u003etimer\nafter a rcu grace period. This requires a rcu_head addition\nto the \"struct bpf_hrtimer\". Another kfree(t) happens in bpf_timer_init,\nthis does not need a kfree_rcu because it is still under the\nspin_lock and timer-\u003etimer has not been visible by others yet.\n\nIn bpf_timer_cancel, rcu_read_lock() is added because this helper\ncan be used in a non rcu critical section context (e.g. from\na sleepable bpf prog). Other timer-\u003etimer usages in helpers.c\nhave been audited, bpf_timer_cancel() is the only place where\ntimer-\u003etimer is used outside of the spin_lock.\n\nAnother solution considered is to mark a t-\u003eflag in bpf_timer_cancel\nand clear it after hrtimer_cancel() is done.  In bpf_timer_cancel_and_free,\nit busy waits for the flag to be cleared before kfree(t). This patch\ngoes with a straight forward solution and frees timer-\u003etimer after\na rcu grace period."
          }
        ]
      },
      "generator": {
        "engine": "bippy-d3b290d2becc"
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "n/a"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://git.kernel.org/stable/c/5268bb02107b9eedfdcd51db75b407d10043368c",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/5268bb02107b9eedfdcd51db75b407d10043368c"
          },
          {
            "name": "https://git.kernel.org/stable/c/addf5e297e6cbf5341f9c07720693ca9ba0057b5",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/addf5e297e6cbf5341f9c07720693ca9ba0057b5"
          },
          {
            "name": "https://git.kernel.org/stable/c/8327ed12e8ebc5436bfaa1786c49988894f9c8a6",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/8327ed12e8ebc5436bfaa1786c49988894f9c8a6"
          },
          {
            "name": "https://git.kernel.org/stable/c/7d80a9e745fa5b47da3bca001f186c02485c7c33",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/7d80a9e745fa5b47da3bca001f186c02485c7c33"
          },
          {
            "name": "https://git.kernel.org/stable/c/0281b919e175bb9c3128bd3872ac2903e9436e3f",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/0281b919e175bb9c3128bd3872ac2903e9436e3f"
          }
        ]
      }
    },
    "nvd.nist.gov": {
      "cve": {
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel\n\nThe following race is possible between bpf_timer_cancel_and_free\nand bpf_timer_cancel. It will lead a UAF on the timer-\u003etimer.\n\nbpf_timer_cancel();\n\tspin_lock();\n\tt = timer-\u003etime;\n\tspin_unlock();\n\n\t\t\t\t\tbpf_timer_cancel_and_free();\n\t\t\t\t\t\tspin_lock();\n\t\t\t\t\t\tt = timer-\u003etimer;\n\t\t\t\t\t\ttimer-\u003etimer = NULL;\n\t\t\t\t\t\tspin_unlock();\n\t\t\t\t\t\thrtimer_cancel(\u0026t-\u003etimer);\n\t\t\t\t\t\tkfree(t);\n\n\t/* UAF on t */\n\thrtimer_cancel(\u0026t-\u003etimer);\n\nIn bpf_timer_cancel_and_free, this patch frees the timer-\u003etimer\nafter a rcu grace period. This requires a rcu_head addition\nto the \"struct bpf_hrtimer\". Another kfree(t) happens in bpf_timer_init,\nthis does not need a kfree_rcu because it is still under the\nspin_lock and timer-\u003etimer has not been visible by others yet.\n\nIn bpf_timer_cancel, rcu_read_lock() is added because this helper\ncan be used in a non rcu critical section context (e.g. from\na sleepable bpf prog). Other timer-\u003etimer usages in helpers.c\nhave been audited, bpf_timer_cancel() is the only place where\ntimer-\u003etimer is used outside of the spin_lock.\n\nAnother solution considered is to mark a t-\u003eflag in bpf_timer_cancel\nand clear it after hrtimer_cancel() is done.  In bpf_timer_cancel_and_free,\nit busy waits for the flag to be cleared before kfree(t). This patch\ngoes with a straight forward solution and frees timer-\u003etimer after\na rcu grace period."
          }
        ],
        "id": "CVE-2024-26737",
        "lastModified": "2024-04-03T17:24:18.150",
        "metrics": {},
        "published": "2024-04-03T17:15:51.243",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/0281b919e175bb9c3128bd3872ac2903e9436e3f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/5268bb02107b9eedfdcd51db75b407d10043368c"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/7d80a9e745fa5b47da3bca001f186c02485c7c33"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/8327ed12e8ebc5436bfaa1786c49988894f9c8a6"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/addf5e297e6cbf5341f9c07720693ca9ba0057b5"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Awaiting Analysis"
      }
    }
  }
}



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