{ "containers": { "cna": { "providerMetadata": { "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038" }, "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->base.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's 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->asoc->ep, 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->asoc->ep, 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't 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->base.sk in sctp_assocs_seq_show() and sctp_rcv().\n\nThanks Jones to bring this issue up.\n\nv1->v2:\n - improve the changelog.\n - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sctp/sctp.h", "include/net/sctp/structs.h", "net/sctp/diag.c", "net/sctp/endpointola.c", "net/sctp/socket.c" ], "versions": [ { "version": "d25adbeb0cdb", "lessThan": "8873140f95d4", "status": "affected", "versionType": "git" }, { "version": "d25adbeb0cdb", "lessThan": "af6e6e58f7eb", "status": "affected", "versionType": "git" }, { "version": "d25adbeb0cdb", "lessThan": "831de271452b", "status": "affected", "versionType": "git" }, { "version": "d25adbeb0cdb", "lessThan": "769d14abd35e", "status": "affected", "versionType": "git" }, { "version": "d25adbeb0cdb", "lessThan": "75799e71df1d", "status": "affected", "versionType": "git" }, { "version": "d25adbeb0cdb", "lessThan": "5ec7d18d1813", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sctp/sctp.h", "include/net/sctp/structs.h", "net/sctp/diag.c", "net/sctp/endpointola.c", "net/sctp/socket.c" ], "versions": [ { "version": "4.14", "status": "affected" }, { "version": "0", "lessThan": "4.14", "status": "unaffected", "versionType": "custom" }, { "version": "4.14.261", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "custom" }, { "version": "4.19.224", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.4.170", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.10.90", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.15.13", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "custom" }, { "version": "5.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e" }, { "url": "https://git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec" }, { "url": "https://git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5" }, { "url": "https://git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ff" }, { "url": "https://git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561d" }, { "url": "https://git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbb" } ], "title": "sctp: use call_rcu to free endpoint", "x_generator": { "engine": "bippy-a5840b7849dd" } } }, "cveMetadata": { "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038", "cveID": "CVE-2021-46929", "requesterUserId": "gregkh@kernel.org", "serial": "1", "state": "PUBLISHED" }, "dataType": "CVE_RECORD", "dataVersion": "5.0" }