cve/published/2024/CVE-2024-49940.json

{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: prevent possible tunnel refcount underflow\n\nWhen a session is created, it sets a backpointer to its tunnel. When\nthe session refcount drops to 0, l2tp_session_free drops the tunnel\nrefcount if session->tunnel is non-NULL. However, session->tunnel is\nset in l2tp_session_create, before the tunnel refcount is incremented\nby l2tp_session_register, which leaves a small window where\nsession->tunnel is non-NULL when the tunnel refcount hasn't been\nbumped.\n\nMoving the assignment to l2tp_session_register is trivial but\nl2tp_session_create calls l2tp_session_set_header_len which uses\nsession->tunnel to get the tunnel's encap. Add an encap arg to\nl2tp_session_set_header_len to avoid using session->tunnel.\n\nIf l2tpv3 sessions have colliding IDs, it is possible for\nl2tp_v3_session_get to race with l2tp_session_register and fetch a\nsession which doesn't yet have session->tunnel set. Add a check for\nthis case."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "net/l2tp/l2tp_core.c",
                  "net/l2tp/l2tp_core.h",
                  "net/l2tp/l2tp_netlink.c",
                  "net/l2tp/l2tp_ppp.c"
               ],
               "versions": [
                  {
                     "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
                     "lessThan": "f7415e60c25a6108cd7955a20b2e66b6251ffe02",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
                     "lessThan": "24256415d18695b46da06c93135f5b51c548b950",
                     "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/l2tp/l2tp_core.c",
                  "net/l2tp/l2tp_core.h",
                  "net/l2tp/l2tp_netlink.c",
                  "net/l2tp/l2tp_ppp.c"
               ],
               "versions": [
                  {
                     "version": "6.11.3",
                     "lessThanOrEqual": "6.11.*",
                     "status": "unaffected",
                     "versionType": "semver"
                  },
                  {
                     "version": "6.12",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "cpeApplicability": [
            {
               "nodes": [
                  {
                     "operator": "OR",
                     "negate": false,
                     "cpeMatch": [
                        {
                           "vulnerable": true,
                           "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                           "versionEndExcluding": "6.11.3"
                        },
                        {
                           "vulnerable": true,
                           "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                           "versionEndExcluding": "6.12"
                        }
                     ]
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02"
            },
            {
               "url": "https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950"
            }
         ],
         "title": "l2tp: prevent possible tunnel refcount underflow",
         "x_generator": {
            "engine": "bippy-1.2.0"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2024-49940",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}