FKIE_CVE-2026-98643

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-19 10:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix out-of-bounds read of rtt_min in sock_ops A sockops prog reading skops->rtt_min never checks the sk type: on the tcp_conn_request() path sock_ops->sk is a request_sock (non-full), and the ctx rewrite casts it to a tcp_sock (full) and reads rtt_min past the end of the request_sock, returning dirty adjacent memory. SEC("sockops") int prog(struct bpf_sock_ops *skops) { switch (skops->op) { case BPF_SOCK_OPS_RWND_INIT: leak = skops->rtt_min; /* reads the request_sock OOB */ ... } } For instance one such read returned rtt_min=0xffff8881, the high half of a leaked kernel pointer. Guarding that cast is exactly what SOCK_OPS_GET_FIELD() does -- it checks is_locked_tcp_sock and returns 0 when sock_ops->sk is not a locked full socket. Every other tcp_sock field in sock_ops goes through it; rtt_min is the only one open-coded, so it skips the check. Read rtt_min through SOCK_OPS_GET_FIELD() too. rtt_min is a bit special: it is a struct minmax and we only want the current min, so pass rtt_min.s[0].v. That is equivalent to the old hand-computed offset offsetof(struct tcp_sock, rtt_min) + sizeof_field(struct minmax_sample, t) (s[0] sits at rtt_min + 0 and .v at + sizeof(.t), i.e. what minmax_get() returns), so the loaded field is unchanged and only the full-sock guard is added. The two BUILD_BUG_ON()s that protected the hand-computed offset are no longer needed. Before patch: 0: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 1: r1 = *(u32 *)(r1 +2324) ; ((tcp_sock *)sk)->rtt_min.s[0].v After patch: 0: *(u64 *)(r1 +56) = r9 1: r9 = *(u8 *)(r1 +50) ; is_locked_tcp_sock 2: if r9 == 0 goto pc+4 ; not a locked full sock -> 0 3: r9 = *(u64 *)(r1 +56) 4: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 5: r1 = *(u32 *)(r1 +2324) ; rtt_min.s[0].v 6: goto pc+2 7: r9 = *(u64 *)(r1 +56) 8: r1 = 0
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0c796efa919f52f788c22c79d1f1b70321696b3d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6785313d4fac96afb21ef193610c1fa88b1a9e64
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a8a9becbac93a9f54f4d565f1f3005eb08a7912f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cba54d142c43ec96d8c4d566f66439e8c0afded7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0c796efa919f52f788c22c79d1f1b70321696b3d",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "a8a9becbac93a9f54f4d565f1f3005eb08a7912f",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "6785313d4fac96afb21ef193610c1fa88b1a9e64",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "cba54d142c43ec96d8c4d566f66439e8c0afded7",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            },
            {
              "lessThan": "75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03",
              "status": "affected",
              "version": "44f0e43037d3a17b043843ba67610ac7c7e37db6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.16"
            },
            {
              "lessThan": "4.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix out-of-bounds read of rtt_min in sock_ops\n\nA sockops prog reading skops-\u003ertt_min never checks the sk type: on the\ntcp_conn_request() path sock_ops-\u003esk is a request_sock (non-full), and the\nctx rewrite casts it to a tcp_sock (full) and reads rtt_min past the end of\nthe request_sock, returning dirty adjacent memory.\n\n\tSEC(\"sockops\")\n\tint prog(struct bpf_sock_ops *skops)\n\t{\n\t\tswitch (skops-\u003eop) {\n\t\tcase BPF_SOCK_OPS_RWND_INIT:\n\t\t\tleak = skops-\u003ertt_min;   /* reads the request_sock OOB */\n\t\t...\n\t\t}\n\t}\n\nFor instance one such read returned rtt_min=0xffff8881, the high half of a\nleaked kernel pointer.\n\nGuarding that cast is exactly what SOCK_OPS_GET_FIELD() does -- it checks\nis_locked_tcp_sock and returns 0 when sock_ops-\u003esk is not a locked full\nsocket. Every other tcp_sock field in sock_ops goes through it; rtt_min is\nthe only one open-coded, so it skips the check.\n\nRead rtt_min through SOCK_OPS_GET_FIELD() too. rtt_min is a bit special:\nit is a struct minmax and we only want the current min, so pass\nrtt_min.s[0].v. That is equivalent to the old hand-computed offset\n\n\toffsetof(struct tcp_sock, rtt_min) + sizeof_field(struct minmax_sample, t)\n\n(s[0] sits at rtt_min + 0 and .v at + sizeof(.t), i.e. what minmax_get()\nreturns), so the loaded field is unchanged and only the full-sock guard is\nadded. The two BUILD_BUG_ON()s that protected the hand-computed offset\nare no longer needed.\n\nBefore patch:\n\n\t0: r1 = *(u64 *)(r1 +0)      ; r1 = skops-\u003esk\n\t1: r1 = *(u32 *)(r1 +2324)   ; ((tcp_sock *)sk)-\u003ertt_min.s[0].v\n\nAfter patch:\n\n\t0: *(u64 *)(r1 +56) = r9\n\t1: r9 = *(u8 *)(r1 +50)      ; is_locked_tcp_sock\n\t2: if r9 == 0 goto pc+4      ; not a locked full sock -\u003e 0\n\t3: r9 = *(u64 *)(r1 +56)\n\t4: r1 = *(u64 *)(r1 +0)      ; r1 = skops-\u003esk\n\t5: r1 = *(u32 *)(r1 +2324)   ; rtt_min.s[0].v\n\t6: goto pc+2\n\t7: r9 = *(u64 *)(r1 +56)\n\t8: r1 = 0"
    }
  ],
  "id": "CVE-2026-98643",
  "lastModified": "2026-10-19T10:19:28.573",
  "metrics": {},
  "published": "2026-10-18T16:17:17.490",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0c796efa919f52f788c22c79d1f1b70321696b3d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6785313d4fac96afb21ef193610c1fa88b1a9e64"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a8a9becbac93a9f54f4d565f1f3005eb08a7912f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cba54d142c43ec96d8c4d566f66439e8c0afded7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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