CVE-2021-46929
Vulnerability from cvelistv5
Published
2024-02-27 09:43
Modified
2024-09-11 17:33
Severity
Summary
sctp: use call_rcu to free endpoint
References
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"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."
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"nvd": "{\"cve\":{\"id\":\"CVE-2021-46929\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-02-27T10:15:07.573\",\"lastModified\":\"2024-04-10T17:05:51.133\",\"vulnStatus\":\"Analyzed\",\"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.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.14.0\",\"versionEndExcluding\":\"4.14.261\",\"matchCriteriaId\":\"D04E4F21-CE5F-4E9D-A182-492968E35204\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.15.0\",\"versionEndExcluding\":\"4.19.224\",\"matchCriteriaId\":\"B34A1353-506A-4AB9-87EC-CD50F09DFB8A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.20.0\",\"versionEndExcluding\":\"5.4.170\",\"matchCriteriaId\":\"56D16FBB-453E-4316-A027-E517828203D7\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.5.0\",\"versionEndExcluding\":\"5.10.90\",\"matchCriteriaId\":\"C87FB3FD-3E74-4588-A1A4-B9BA8AE0C06B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11.0\",\"versionEndExcluding\":\"5.15.13\",\"matchCriteriaId\":\"083E0940-932B-447B-A6B2-677DAE27FD04\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ff\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
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