fkie_cve-2021-46936
Vulnerability from fkie_nvd
Published
2024-02-27 10:15
Modified
2024-11-21 06:34
Summary
In the Linux kernel, the following vulnerability has been resolved: net: fix use-after-free in tw_timer_handler A real world panic issue was found as follow in Linux 5.4. BUG: unable to handle page fault for address: ffffde49a863de28 PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0 RIP: 0010:tw_timer_handler+0x20/0x40 Call Trace: <IRQ> call_timer_fn+0x2b/0x120 run_timer_softirq+0x1ef/0x450 __do_softirq+0x10d/0x2b8 irq_exit+0xc7/0xd0 smp_apic_timer_interrupt+0x68/0x120 apic_timer_interrupt+0xf/0x20 This issue was also reported since 2017 in the thread [1], unfortunately, the issue was still can be reproduced after fixing DCCP. The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net namespace is destroyed since tcp_sk_ops is registered befrore ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops in the list of pernet_list. There will be a use-after-free on net->mib.net_statistics in tw_timer_handler after ipv4_mib_exit_net if there are some inflight time-wait timers. This bug is not introduced by commit f2bf415cfed7 ("mib: add net to NET_ADD_STATS_BH") since the net_statistics is a global variable instead of dynamic allocation and freeing. Actually, commit 61a7e26028b9 ("mib: put net statistics on struct net") introduces the bug since it put net statistics on struct net and free it when net namespace is destroyed. Moving init_ipv4_mibs() to the front of tcp_init() to fix this bug and replace pr_crit() with panic() since continuing is meaningless when init_ipv4_mibs() fails. [1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2386e81a1d277f540e1285565c9d41d531bb69d4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5c2fe20ad37ff56070ae0acb34152333976929b4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a8e1944b44f94f5c5f530e434c5eaee787254566Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e73164e89d1be561228a4534e1091369ee4ba41aPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fe5838c22b986c1190f1dce9aa09bf6a491c1a69Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/2386e81a1d277f540e1285565c9d41d531bb69d4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/5c2fe20ad37ff56070ae0acb34152333976929b4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/a8e1944b44f94f5c5f530e434c5eaee787254566Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/e73164e89d1be561228a4534e1091369ee4ba41aPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/fe5838c22b986c1190f1dce9aa09bf6a491c1a69Patch



{
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: fix use-after-free in tw_timer_handler\n\nA real world panic issue was found as follow in Linux 5.4.\n\n    BUG: unable to handle page fault for address: ffffde49a863de28\n    PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0\n    RIP: 0010:tw_timer_handler+0x20/0x40\n    Call Trace:\n     \u003cIRQ\u003e\n     call_timer_fn+0x2b/0x120\n     run_timer_softirq+0x1ef/0x450\n     __do_softirq+0x10d/0x2b8\n     irq_exit+0xc7/0xd0\n     smp_apic_timer_interrupt+0x68/0x120\n     apic_timer_interrupt+0xf/0x20\n\nThis issue was also reported since 2017 in the thread [1],\nunfortunately, the issue was still can be reproduced after fixing\nDCCP.\n\nThe ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net\nnamespace is destroyed since tcp_sk_ops is registered befrore\nipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops\nin the list of pernet_list. There will be a use-after-free on\nnet-\u003emib.net_statistics in tw_timer_handler after ipv4_mib_exit_net\nif there are some inflight time-wait timers.\n\nThis bug is not introduced by commit f2bf415cfed7 (\"mib: add net to\nNET_ADD_STATS_BH\") since the net_statistics is a global variable\ninstead of dynamic allocation and freeing. Actually, commit\n61a7e26028b9 (\"mib: put net statistics on struct net\") introduces\nthe bug since it put net statistics on struct net and free it when\nnet namespace is destroyed.\n\nMoving init_ipv4_mibs() to the front of tcp_init() to fix this bug\nand replace pr_crit() with panic() since continuing is meaningless\nwhen init_ipv4_mibs() fails.\n\n[1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: net: corrige use-after-free en tw_timer_handler Se encontr\u00f3 un problema de p\u00e1nico en el mundo real como se muestra a continuaci\u00f3n en Linux 5.4. ERROR: no se puede manejar el error de p\u00e1gina para la direcci\u00f3n: ffffde49a863de28 PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0 RIP: 0010:tw_timer_handler+0x20/0x40 Seguimiento de llamadas:  call_timer_fn+0x2b/ 0x120 run_timer_softirq+0x1ef/0x450 __do_softirq+0x10d/ 0x2b8 irq_exit+0xc7/0xd0 smp_apic_timer_interrupt+0x68/0x120 apic_timer_interrupt+0xf/0x20 Este problema tambi\u00e9n se inform\u00f3 desde 2017 en el hilo [1], desafortunadamente, el problema a\u00fan se puede reproducir despu\u00e9s de corregir DCCP. ipv4_mib_exit_net se llama antes de tcp_sk_exit_batch cuando se destruye un espacio de nombres de red, ya que tcp_sk_ops est\u00e1 registrado antes de ipv4_mib_ops, lo que significa que tcp_sk_ops est\u00e1 al frente de ipv4_mib_ops en la lista de pernet_list. Habr\u00e1 un use-after-free en net-\u0026gt;mib.net_statistics en tw_timer_handler despu\u00e9s de ipv4_mib_exit_net si hay algunos temporizadores de espera a bordo. Este error no se introduce mediante la confirmaci\u00f3n f2bf415cfed7 (\"mib: add net to NET_ADD_STATS_BH\") ya que net_statistics es una variable global en lugar de una asignaci\u00f3n y liberaci\u00f3n din\u00e1micas. En realidad, la confirmaci\u00f3n 61a7e26028b9 (\"mib: poner estad\u00edsticas de red en struct net\") introduce el error ya que coloca estad\u00edsticas de red en struct net y las libera cuando se destruye el espacio de nombres de red. Mover init_ipv4_mibs() al frente de tcp_init() para corregir este error y reemplazar pr_crit() con p\u00e1nico() ya que continuar no tiene sentido cuando init_ipv4_mibs() falla. [1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1"
    }
  ],
  "id": "CVE-2021-46936",
  "lastModified": "2024-11-21T06:34:58.357",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2024-02-27T10:15:08.017",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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