CVE-2021-46936 (GCVE-0-2021-46936)
Vulnerability from cvelistv5
Published
2024-02-27 09:44
Modified
2025-05-04 07:00
Severity ?
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-8c081fb06d67 https://git.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/2386e81a1d277f540e1285565c9d41d531bb69d4 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/5c2fe20ad37ff56070ae0acb34152333976929b4 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/a8e1944b44f94f5c5f530e434c5eaee787254566 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0 Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/e73164e89d1be561228a4534e1091369ee4ba41a Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67 https://git.kernel.org/stable/c/fe5838c22b986c1190f1dce9aa09bf6a491c1a69 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/2386e81a1d277f540e1285565c9d41d531bb69d4 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/5c2fe20ad37ff56070ae0acb34152333976929b4 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/a8e1944b44f94f5c5f530e434c5eaee787254566 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0 Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/e73164e89d1be561228a4534e1091369ee4ba41a Patch
af854a3a-2127-422b-91ae-364da2661108 https://git.kernel.org/stable/c/fe5838c22b986c1190f1dce9aa09bf6a491c1a69 Patch
Impacted products
Vendor Product Version
Linux Linux Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
Version: 61a7e26028b94805fd686a6dc9dbd9941f8f19b0
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    "nvd": "{\"cve\":{\"id\":\"CVE-2021-46936\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-02-27T10:15:08.017\",\"lastModified\":\"2024-11-21T06:34:58.357\",\"vulnStatus\":\"Modified\",\"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. 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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. 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      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
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  }
}


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