fkie_cve-2021-46929
Vulnerability from fkie_nvd
Published
2024-02-27 10:15
Modified
2024-11-21 06:34
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: sctp: use call_rcu to free endpoint This patch is to delay the endpoint free by calling call_rcu() to fix another use-after-free issue in sctp_sock_dump(): BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 Call Trace: __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] __lock_sock+0x203/0x350 net/core/sock.c:2253 lock_sock_nested+0xfe/0x120 net/core/sock.c:2774 lock_sock include/net/sock.h:1492 [inline] sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324 sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091 sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527 __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049 inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065 netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244 __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352 netlink_dump_start include/linux/netlink.h:216 [inline] inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170 __sock_diag_cmd net/core/sock_diag.c:232 [inline] sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274 This issue occurs when asoc is peeled off and the old sk is freed after getting it by asoc->base.sk and before calling lock_sock(sk). To prevent the sk free, as a holder of the sk, ep should be alive when calling lock_sock(). This patch uses call_rcu() and moves sock_put and ep free into sctp_endpoint_destroy_rcu(), so that it's safe to try to hold the ep under rcu_read_lock in sctp_transport_traverse_process(). If sctp_endpoint_hold() returns true, it means this ep is still alive and we have held it and can continue to dump it; If it returns false, it means this ep is dead and can be freed after rcu_read_unlock, and we should skip it. In sctp_sock_dump(), after locking the sk, if this ep is different from tsp->asoc->ep, it means during this dumping, this asoc was peeled off before calling lock_sock(), and the sk should be skipped; If this ep is the same with tsp->asoc->ep, it means no peeloff happens on this asoc, and due to lock_sock, no peeloff will happen either until release_sock. Note that delaying endpoint free won't delay the port release, as the port release happens in sctp_endpoint_destroy() before calling call_rcu(). Also, freeing endpoint by call_rcu() makes it safe to access the sk by asoc->base.sk in sctp_assocs_seq_show() and sctp_rcv(). Thanks Jones to bring this issue up. v1->v2: - improve the changelog. - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbbPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561dPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ffPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3ePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ecPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbbPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561dPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ffPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3ePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ecPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

{
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsctp: use call_rcu to free endpoint\n\nThis patch is to delay the endpoint free by calling call_rcu() to fix\nanother use-after-free issue in sctp_sock_dump():\n\n  BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20\n  Call Trace:\n    __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218\n    lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844\n    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]\n    _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168\n    spin_lock_bh include/linux/spinlock.h:334 [inline]\n    __lock_sock+0x203/0x350 net/core/sock.c:2253\n    lock_sock_nested+0xfe/0x120 net/core/sock.c:2774\n    lock_sock include/net/sock.h:1492 [inline]\n    sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324\n    sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091\n    sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527\n    __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049\n    inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065\n    netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244\n    __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352\n    netlink_dump_start include/linux/netlink.h:216 [inline]\n    inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170\n    __sock_diag_cmd net/core/sock_diag.c:232 [inline]\n    sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263\n    netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477\n    sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274\n\nThis issue occurs when asoc is peeled off and the old sk is freed after\ngetting it by asoc-\u003ebase.sk and before calling lock_sock(sk).\n\nTo prevent the sk free, as a holder of the sk, ep should be alive when\ncalling lock_sock(). This patch uses call_rcu() and moves sock_put and\nep free into sctp_endpoint_destroy_rcu(), so that it\u0027s safe to try to\nhold the ep under rcu_read_lock in sctp_transport_traverse_process().\n\nIf sctp_endpoint_hold() returns true, it means this ep is still alive\nand we have held it and can continue to dump it; If it returns false,\nit means this ep is dead and can be freed after rcu_read_unlock, and\nwe should skip it.\n\nIn sctp_sock_dump(), after locking the sk, if this ep is different from\ntsp-\u003easoc-\u003eep, it means during this dumping, this asoc was peeled off\nbefore calling lock_sock(), and the sk should be skipped; If this ep is\nthe same with tsp-\u003easoc-\u003eep, it means no peeloff happens on this asoc,\nand due to lock_sock, no peeloff will happen either until release_sock.\n\nNote that delaying endpoint free won\u0027t delay the port release, as the\nport release happens in sctp_endpoint_destroy() before calling call_rcu().\nAlso, freeing endpoint by call_rcu() makes it safe to access the sk by\nasoc-\u003ebase.sk in sctp_assocs_seq_show() and sctp_rcv().\n\nThanks Jones to bring this issue up.\n\nv1-\u003ev2:\n  - improve the changelog.\n  - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: sctp: use call_rcu para liberar el endpoint. Este parche tiene como objetivo retrasar la liberaci\u00f3n del endpoint llamando a call_rcu() para solucionar otro problema de use-after-free en sctp_sock_dump(): ERROR: KASAN: use-after-free en __lock_acquire+0x36d9/0x4c20 Rastreo de llamadas: __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_bh include/linux/spinlock_api_smp.h :135 [en l\u00ednea] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [en l\u00ednea] __lock_sock+0x203/0x350 net/core/sock.c:2253 lock_sock_nested+0xfe/ 0x120 net/core/sock.c:2774 lock_sock include/net/sock.h:1492 [en l\u00ednea] sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324 sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c: 5091 sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527 __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049 inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065 netlink_dump+0x6 06/0x1080 neto/ netlink/af_netlink.c:2244 __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352 netlink_dump_start include/linux/netlink.h:216 [en l\u00ednea] inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170 __sock_diag_cm re neto /core/sock_diag.c:232 [en l\u00ednea] sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477 sock_diag_rcv+0x2a/0x40 net/core/sock_diag. c:274 Este problema ocurre cuando se quita asoc y se libera el sk antiguo despu\u00e9s de obtenerlo mediante asoc-\u0026gt;base.sk y antes de llamar a lock_sock(sk). Para evitar que sk se libere, como titular de sk, ep debe estar activo al llamar a lock_sock(). Este parche usa call_rcu() y mueve sock_put y ep free a sctp_endpoint_destroy_rcu(), por lo que es seguro intentar mantener el ep bajo rcu_read_lock en sctp_transport_traverse_process(). Si sctp_endpoint_hold() devuelve verdadero, significa que este ep todav\u00eda est\u00e1 vivo, lo hemos retenido y podemos continuar descart\u00e1ndolo; Si devuelve falso, significa que este ep est\u00e1 muerto y puede liberarse despu\u00e9s de rcu_read_unlock, y debemos omitirlo. En sctp_sock_dump(), despu\u00e9s de bloquear el sk, si este ep es diferente de tsp-\u0026gt;asoc-\u0026gt;ep, significa que durante este volcado, este asoc se elimin\u00f3 antes de llamar a lock_sock(), y el sk debe omitirse; Si este ep es el mismo con tsp-\u0026gt;asoc-\u0026gt;ep, significa que no se produce ning\u00fan despegue en este asoc y, debido a lock_sock, tampoco se producir\u00e1 ning\u00fan despegue hasta que se libere_sock. Tenga en cuenta que retrasar la liberaci\u00f3n del endpoint  no retrasar\u00e1 la liberaci\u00f3n del puerto, ya que la liberaci\u00f3n del puerto ocurre en sctp_endpoint_destroy() antes de llamar a call_rcu(). Adem\u00e1s, liberar el endpoint mediante call_rcu() hace que sea seguro acceder a sk mediante asoc-\u0026gt;base.sk en sctp_assocs_seq_show() y sctp_rcv(). Gracias Jones por plantear este problema. v1-\u0026gt;v2: - mejorar el registro de cambios. - agregue kfree(ep) a sctp_endpoint_destroy_rcu(), como not\u00f3 Jakub."
    }
  ],
  "id": "CVE-2021-46929",
  "lastModified": "2024-11-21T06:34:57.380",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2024-02-27T10:15:07.573",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    },
    {
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      "tags": [
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      "url": "https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ff"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec"
    }
  ],
  "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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