CVE-2024-36489 tls: fix missing memory barrier in tls_init

2024-06-2110:18:10

Linux

www.cve.org

linux

kernel

vulnerability

tls

initialization

memory barrier

issue

cve-2024-36489

fix

missing

store-store reordering

0.0004 Low

EPSS

Percentile

10.4%

JSON

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

tls: fix missing memory barrier in tls_init

In tls_init(), a write memory barrier is missing, and store-store
reordering may cause NULL dereference in tls_{setsockopt,getsockopt}.

CPU0 CPU1

// In tls_init()
// In tls_ctx_create()
ctx = kzalloc()
ctx->sk_proto = READ_ONCE(sk->sk_prot) -(1)

// In update_sk_prot()
WRITE_ONCE(sk->sk_prot, tls_prots) -(2)

                               // In sock_common_setsockopt()
                               READ_ONCE(sk-&gt;sk_prot)-&gt;setsockopt()

                               // In tls_{setsockopt,getsockopt}()
                               ctx-&gt;sk_proto-&gt;setsockopt()    -(3)

In the above scenario, when (1) and (2) are reordered, (3) can observe
the NULL value of ctx->sk_proto, causing NULL dereference.

To fix it, we rely on rcu_assign_pointer() which implies the release
barrier semantic. By moving rcu_assign_pointer() after ctx->sk_proto is
initialized, we can ensure that ctx->sk_proto are visible when
changing sk->sk_prot.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/tls/tls_main.c"
    ],
    "versions": [
      {
        "version": "d5bee7374b68",
        "lessThan": "d72e126e9a36",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d5bee7374b68",
        "lessThan": "2c260a24cf1c",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d5bee7374b68",
        "lessThan": "335c8f1566d8",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d5bee7374b68",
        "lessThan": "ab67c2fd3d07",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d5bee7374b68",
        "lessThan": "ef21007a7b58",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d5bee7374b68",
        "lessThan": "91e61dd7a0af",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/tls/tls_main.c"
    ],
    "versions": [
      {
        "version": "5.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.7",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.219",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.161",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.93",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.33",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.4",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10-rc1",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]