fkie_cve-2022-50219
Vulnerability from fkie_nvd
Published
2025-06-18 11:15
Modified
2025-06-18 13:47
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix KASAN use-after-free Read in compute_effective_progs Syzbot found a Use After Free bug in compute_effective_progs(). The reproducer creates a number of BPF links, and causes a fault injected alloc to fail, while calling bpf_link_detach on them. Link detach triggers the link to be freed by bpf_link_free(), which calls __cgroup_bpf_detach() and update_effective_progs(). If the memory allocation in this function fails, the function restores the pointer to the bpf_cgroup_link on the cgroup list, but the memory gets freed just after it returns. After this, every subsequent call to update_effective_progs() causes this already deallocated pointer to be dereferenced in prog_list_length(), and triggers KASAN UAF error. To fix this issue don't preserve the pointer to the prog or link in the list, but remove it and replace it with a dummy prog without shrinking the table. The subsequent call to __cgroup_bpf_detach() or __cgroup_bpf_detach() will correct it.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3527e3cbb84d8868c4d4e91ba55915f96d39ec3d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4c46091ee985ae84c60c5e95055d779fcd291d87
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6336388715afa419cc97d0255bda3bba1b96b7ca
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/be001f9da71eaa3b61e186fb88bde3279728bdca
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix KASAN use-after-free Read in compute_effective_progs\n\nSyzbot found a Use After Free bug in compute_effective_progs().\nThe reproducer creates a number of BPF links, and causes a fault\ninjected alloc to fail, while calling bpf_link_detach on them.\nLink detach triggers the link to be freed by bpf_link_free(),\nwhich calls __cgroup_bpf_detach() and update_effective_progs().\nIf the memory allocation in this function fails, the function restores\nthe pointer to the bpf_cgroup_link on the cgroup list, but the memory\ngets freed just after it returns. After this, every subsequent call to\nupdate_effective_progs() causes this already deallocated pointer to be\ndereferenced in prog_list_length(), and triggers KASAN UAF error.\n\nTo fix this issue don\u0027t preserve the pointer to the prog or link in the\nlist, but remove it and replace it with a dummy prog without shrinking\nthe table. The subsequent call to __cgroup_bpf_detach() or\n__cgroup_bpf_detach() will correct it."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Correcci\u00f3n de la lectura de Use-After-Free de KASAN en compute_effective_progs Syzbot encontr\u00f3 un error de Use-After-Free en compute_effective_progs(). El reproductor crea varios enlaces BPF y provoca que falle una asignaci\u00f3n inyectada por error, al llamar a bpf_link_detach en ellos. La separaci\u00f3n del enlace activa la liberaci\u00f3n del enlace por bpf_link_free(), que llama a __cgroup_bpf_detach() y update_effective_progs(). Si la asignaci\u00f3n de memoria en esta funci\u00f3n falla, la funci\u00f3n restaura el puntero a bpf_cgroup_link en la lista cgroup, pero la memoria se libera justo despu\u00e9s de que regrese. Despu\u00e9s de esto, cada llamada posterior a update_effective_progs() hace que este puntero ya desasignado se desreferencia en prog_list_length() y activa el error UAF de KASAN. Para solucionar este problema, no conserve el puntero al programa ni al enlace en la lista, sino elim\u00ednelo y reempl\u00e1celo con un programa ficticio sin reducir la tabla. La llamada posterior a __cgroup_bpf_detach() o __cgroup_bpf_detach() lo corregir\u00e1. "
    }
  ],
  "id": "CVE-2022-50219",
  "lastModified": "2025-06-18T13:47:40.833",
  "metrics": {},
  "published": "2025-06-18T11:15:52.863",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1f8ca9c40e6222ce431e9ba5dae3cccce8ef9443"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3527e3cbb84d8868c4d4e91ba55915f96d39ec3d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4c46091ee985ae84c60c5e95055d779fcd291d87"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6336388715afa419cc97d0255bda3bba1b96b7ca"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/be001f9da71eaa3b61e186fb88bde3279728bdca"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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