{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-38463",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2025-38463"
  ],
  "published": "2025-07-25T15:35:02Z",
  "summary": "tcp: Correct signedness in skb remaining space calculation",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Correct signedness in skb remaining space calculation\n\nSyzkaller reported a bug [1] where sk->sk_forward_alloc can overflow.\n\nWhen we send data, if an skb exists at the tail of the write queue, the\nkernel will attempt to append the new data to that skb. However, the code\nthat checks for available space in the skb is flawed:\n'''\ncopy = size_goal - skb->len\n'''\n\nThe types of the variables involved are:\n'''\ncopy: ssize_t (s64 on 64-bit systems)\nsize_goal: int\nskb->len: unsigned int\n'''\n\nDue to C's type promotion rules, the signed size_goal is converted to an\nunsigned int to match skb->len before the subtraction. The result is an\nunsigned int.\n\nWhen this unsigned int result is then assigned to the s64 copy variable,\nit is zero-extended, preserving its non-negative value. Consequently, copy\nis always >= 0.\n\nAssume we are sending 2GB of data and size_goal has been adjusted to a\nvalue smaller than skb->len. The subtraction will result in copy holding a\nvery large positive integer. In the subsequent logic, this large value is\nused to update sk->sk_forward_alloc, which can easily cause it to overflow.\n\nThe syzkaller reproducer uses TCP_REPAIR to reliably create this\ncondition. However, this can also occur in real-world scenarios. The\ntcp_bound_to_half_wnd() function can also reduce size_goal to a small\nvalue. This would cause the subsequent tcp_wmem_schedule() to set\nsk->sk_forward_alloc to a value close to INT_MAX. Further memory\nallocation requests would then cause sk_forward_alloc to wrap around and\nbecome negative.\n\n[1]: https://syzkaller.appspot.com/bug?extid=de6565462ab540f50e47",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.6.20-1+rpt1",
        "1:6.6.28-1+rpt1",
        "1:6.6.31-1+rpt1",
        "1:6.6.47-1+rpt1",
        "1:6.6.51-1+rpt1",
        "1:6.6.51-1+rpt2",
        "1:6.6.51-1+rpt3",
        "1:6.6.62-1+rpt1",
        "1:6.6.74-1+rpt1",
        "1:6.12.20-1+rpt1~bpo12+1",
        "1:6.12.25-1+rpt1",
        "1:6.12.34-1+rpt1~bookworm"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-2712",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v6",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v7l",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.20+rpt-rpi-v8",
            "binary_version": "1:6.6.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-2712",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-v6",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-v7",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-v7l",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.28+rpt-rpi-v8",
            "binary_version": "1:6.6.28-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.31+rpt-rpi-2712",
            "binary_version": "1:6.6.31-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.31+rpt-rpi-v6",
            "binary_version": "1:6.6.31-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.31+rpt-rpi-v7",
            "binary_version": "1:6.6.31-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.31+rpt-rpi-v7l",
            "binary_version": "1:6.6.31-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.31+rpt-rpi-v8",
            "binary_version": "1:6.6.31-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.47+rpt-rpi-2712",
            "binary_version": "1:6.6.47-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.47+rpt-rpi-v6",
            "binary_version": "1:6.6.47-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.47+rpt-rpi-v7",
            "binary_version": "1:6.6.47-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.47+rpt-rpi-v7l",
            "binary_version": "1:6.6.47-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.47+rpt-rpi-v8",
            "binary_version": "1:6.6.47-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-2712",
            "binary_version": "1:6.6.51-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v6",
            "binary_version": "1:6.6.51-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7",
            "binary_version": "1:6.6.51-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7l",
            "binary_version": "1:6.6.51-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v8",
            "binary_version": "1:6.6.51-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-2712",
            "binary_version": "1:6.6.51-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v6",
            "binary_version": "1:6.6.51-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7",
            "binary_version": "1:6.6.51-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7l",
            "binary_version": "1:6.6.51-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v8",
            "binary_version": "1:6.6.51-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-2712",
            "binary_version": "1:6.6.51-1+rpt3"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v6",
            "binary_version": "1:6.6.51-1+rpt3"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7",
            "binary_version": "1:6.6.51-1+rpt3"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v7l",
            "binary_version": "1:6.6.51-1+rpt3"
          },
          {
            "binary_name": "linux-image-6.6.51+rpt-rpi-v8",
            "binary_version": "1:6.6.51-1+rpt3"
          },
          {
            "binary_name": "linux-image-6.6.62+rpt-rpi-2712",
            "binary_version": "1:6.6.62-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.62+rpt-rpi-v6",
            "binary_version": "1:6.6.62-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.62+rpt-rpi-v7",
            "binary_version": "1:6.6.62-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.62+rpt-rpi-v7l",
            "binary_version": "1:6.6.62-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.62+rpt-rpi-v8",
            "binary_version": "1:6.6.62-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.74+rpt-rpi-2712",
            "binary_version": "1:6.6.74-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.74+rpt-rpi-v6",
            "binary_version": "1:6.6.74-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.74+rpt-rpi-v7",
            "binary_version": "1:6.6.74-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.74+rpt-rpi-v7l",
            "binary_version": "1:6.6.74-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.6.74+rpt-rpi-v8",
            "binary_version": "1:6.6.74-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-2712",
            "binary_version": "1:6.12.20-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v6",
            "binary_version": "1:6.12.20-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v7",
            "binary_version": "1:6.12.20-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v7l",
            "binary_version": "1:6.12.20-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v8",
            "binary_version": "1:6.12.20-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-2712",
            "binary_version": "1:6.12.25-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v6",
            "binary_version": "1:6.12.25-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v7",
            "binary_version": "1:6.12.25-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v7l",
            "binary_version": "1:6.12.25-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v8",
            "binary_version": "1:6.12.25-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-2712",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v6",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v7",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v7l",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v8",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v8-rt",
            "binary_version": "1:6.12.34-1+rpt1~bookworm"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.6.20-1+rpt1": {
            "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668",
            "upstream_version": "6.6.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.28-1+rpt1": {
            "linux_commit": "0c341f47adc3578cd5f817aa20ee2b7f9ae6b23e",
            "upstream_version": "6.6.28",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.31-1+rpt1": {
            "linux_commit": "c1432b4bae5b6582f4d32ba381459f33c34d1424",
            "upstream_version": "6.6.31",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.47-1+rpt1": {
            "linux_commit": "cf64a1dfecc2dc418efdd61701c1a4b185ab4761",
            "upstream_version": "6.6.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.51-1+rpt1": {
            "linux_commit": "0094eba3f2a4338cfa6854b0b5104d02ba0fa01f",
            "upstream_version": "6.6.51",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.51-1+rpt2": {
            "linux_commit": "82a50e430ef1d6eb37d78e25aa572c1f6ea56160",
            "upstream_version": "6.6.51",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.51-1+rpt3": {
            "linux_commit": "5aeecea9f4a45248bcf564dec924965e066a7bfd",
            "upstream_version": "6.6.51",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.62-1+rpt1": {
            "linux_commit": "dd2394360860d15146c96635796a75b05bb32b61",
            "upstream_version": "6.6.62",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.6.74-1+rpt1": {
            "linux_commit": "a18d9ced4965462cb7b3b4252ada440395105308",
            "upstream_version": "6.6.74",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.6.99"
          },
          "1:6.12.20-1+rpt1~bpo12+1": {
            "linux_commit": "cd231d4775b14f228606c09f219b48308f6ab3aa",
            "upstream_version": "6.12.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.25-1+rpt1": {
            "linux_commit": "3dd2c2c507c271d411fab2e82a2b3b7e0b6d3f16",
            "upstream_version": "6.12.25",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.34-1+rpt1~bookworm": {
            "linux_commit": "8f77e03530f65209a377d25023e912b288e039cd",
            "upstream_version": "6.12.34",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          }
        }
      }
    },
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.12.19-1+rpt1~bpo12+1",
        "1:6.12.19-1+rpt1",
        "1:6.12.20-1+rpt1",
        "1:6.12.25-1+rpt1+trixie",
        "1:6.12.34-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-2712",
            "binary_version": "1:6.12.19-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v6",
            "binary_version": "1:6.12.19-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v7",
            "binary_version": "1:6.12.19-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v7l",
            "binary_version": "1:6.12.19-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v8",
            "binary_version": "1:6.12.19-1+rpt1~bpo12+1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-2712",
            "binary_version": "1:6.12.19-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v6",
            "binary_version": "1:6.12.19-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v7",
            "binary_version": "1:6.12.19-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v7l",
            "binary_version": "1:6.12.19-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.19+rpt-rpi-v8",
            "binary_version": "1:6.12.19-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-2712",
            "binary_version": "1:6.12.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v6",
            "binary_version": "1:6.12.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v7",
            "binary_version": "1:6.12.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v7l",
            "binary_version": "1:6.12.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.20+rpt-rpi-v8",
            "binary_version": "1:6.12.20-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-2712",
            "binary_version": "1:6.12.25-1+rpt1+trixie"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v6",
            "binary_version": "1:6.12.25-1+rpt1+trixie"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v7",
            "binary_version": "1:6.12.25-1+rpt1+trixie"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v8",
            "binary_version": "1:6.12.25-1+rpt1+trixie"
          },
          {
            "binary_name": "linux-image-6.12.25+rpt-rpi-v8-rt",
            "binary_version": "1:6.12.25-1+rpt1+trixie"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-2712",
            "binary_version": "1:6.12.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v6",
            "binary_version": "1:6.12.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v7",
            "binary_version": "1:6.12.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v8",
            "binary_version": "1:6.12.34-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.34+rpt-rpi-v8-rt",
            "binary_version": "1:6.12.34-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.12.19-1+rpt1~bpo12+1": {
            "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0",
            "upstream_version": "6.12.19",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.19-1+rpt1": {
            "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0",
            "upstream_version": "6.12.19",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.20-1+rpt1": {
            "linux_commit": "cd231d4775b14f228606c09f219b48308f6ab3aa",
            "upstream_version": "6.12.20",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.25-1+rpt1+trixie": {
            "linux_commit": "3dd2c2c507c271d411fab2e82a2b3b7e0b6d3f16",
            "upstream_version": "6.12.25",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          },
          "1:6.12.34-1+rpt1": {
            "linux_commit": "8f77e03530f65209a377d25023e912b288e039cd",
            "upstream_version": "6.12.34",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.12.39"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-38463"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/81373cd1d72d87c7d844d4454a526b8f53e72d00"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/62e6160cfb5514787bda833d466509edc38fde23"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9f164fa6bb09fbcc60fa5c3ff551ce9eec1befd7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d3a5f2871adc0c61c61869f37f3e697d97f03d8c"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z"
  }
}