ghsa-5wwp-3576-jfjc
Vulnerability from github
Published
2022-05-24 17:14
Modified
2022-05-24 17:14
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Details

An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the "critical" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.

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{
   affected: [],
   aliases: [
      "CVE-2020-11739",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-119",
         "CWE-362",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2020-04-14T13:15:00Z",
      severity: "MODERATE",
   },
   details: "An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the \"critical\" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.",
   id: "GHSA-5wwp-3576-jfjc",
   modified: "2022-05-24T17:14:11Z",
   published: "2022-05-24T17:14:11Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2020-11739",
      },
      {
         type: "WEB",
         url: "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5M2XRNCHOGGTJQBZQJ7DCV6ZNAKN3LE2",
      },
      {
         type: "WEB",
         url: "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVTP4OYHCTRU3ONFJOFJQVNDFB25KLLG",
      },
      {
         type: "WEB",
         url: "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YMAW7D2MP6RE4BFI5BZWOBBWGY3VSOFN",
      },
      {
         type: "WEB",
         url: "https://security.gentoo.org/glsa/202005-08",
      },
      {
         type: "WEB",
         url: "https://www.debian.org/security/2020/dsa-4723",
      },
      {
         type: "WEB",
         url: "https://xenbits.xen.org/xsa/advisory-314.html",
      },
      {
         type: "WEB",
         url: "http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00006.html",
      },
      {
         type: "WEB",
         url: "http://www.openwall.com/lists/oss-security/2020/04/14/2",
      },
      {
         type: "WEB",
         url: "http://xenbits.xen.org/xsa/advisory-314.html",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
         type: "CVSS_V3",
      },
   ],
}


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