ghsa-qrrc-56f8-gw3j
Vulnerability from github
Published
2025-01-11 15:30
Modified
2025-01-11 15:30
Details

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

bpf: Prevent tailcall infinite loop caused by freplace

There is a potential infinite loop issue that can occur when using a combination of tail calls and freplace.

In an upcoming selftest, the attach target for entry_freplace of tailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in entry_freplace leads to entry_tc. This results in an infinite loop:

entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc.

The problem arises because the tail_call_cnt in entry_freplace resets to zero each time entry_freplace is executed, causing the tail call mechanism to never terminate, eventually leading to a kernel panic.

To fix this issue, the solution is twofold:

  1. Prevent updating a program extended by an freplace program to a prog_array map.
  2. Prevent extending a program that is already part of a prog_array map with an freplace program.

This ensures that:

  • If a program or its subprogram has been extended by an freplace program, it can no longer be updated to a prog_array map.
  • If a program has been added to a prog_array map, neither it nor its subprograms can be extended by an freplace program.

Moreover, an extension program should not be tailcalled. As such, return -EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a prog_array map.

Additionally, fix a minor code style issue by replacing eight spaces with a tab for proper formatting.

Show details on source website


{
  "affected": [],
  "aliases": [
    "CVE-2024-47794"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-01-11T13:15:22Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Prevent tailcall infinite loop caused by freplace\n\nThere is a potential infinite loop issue that can occur when using a\ncombination of tail calls and freplace.\n\nIn an upcoming selftest, the attach target for entry_freplace of\ntailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in\nentry_freplace leads to entry_tc. This results in an infinite loop:\n\nentry_tc -\u003e subprog_tc -\u003e entry_freplace --tailcall-\u003e entry_tc.\n\nThe problem arises because the tail_call_cnt in entry_freplace resets to\nzero each time entry_freplace is executed, causing the tail call mechanism\nto never terminate, eventually leading to a kernel panic.\n\nTo fix this issue, the solution is twofold:\n\n1. Prevent updating a program extended by an freplace program to a\n   prog_array map.\n2. Prevent extending a program that is already part of a prog_array map\n   with an freplace program.\n\nThis ensures that:\n\n* If a program or its subprogram has been extended by an freplace program,\n  it can no longer be updated to a prog_array map.\n* If a program has been added to a prog_array map, neither it nor its\n  subprograms can be extended by an freplace program.\n\nMoreover, an extension program should not be tailcalled. As such, return\n-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a\nprog_array map.\n\nAdditionally, fix a minor code style issue by replacing eight spaces with a\ntab for proper formatting.",
  "id": "GHSA-qrrc-56f8-gw3j",
  "modified": "2025-01-11T15:30:28Z",
  "published": "2025-01-11T15:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-47794"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/987aa730bad3e1ef66d9f30182294daa78f6387d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d6083f040d5d8f8d748462c77e90547097df936e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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