{"id":"CVE-2023-53489","summary":"tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.\n\nsyzkaller reported [0] memory leaks of an UDP socket and ZEROCOPY\nskbs.  We can reproduce the problem with these sequences:\n\n  sk = socket(AF_INET, SOCK_DGRAM, 0)\n  sk.setsockopt(SOL_SOCKET, SO_TIMESTAMPING, SOF_TIMESTAMPING_TX_SOFTWARE)\n  sk.setsockopt(SOL_SOCKET, SO_ZEROCOPY, 1)\n  sk.sendto(b'', MSG_ZEROCOPY, ('127.0.0.1', 53))\n  sk.close()\n\nsendmsg() calls msg_zerocopy_alloc(), which allocates a skb, sets\nskb-\u003ecb-\u003eubuf.refcnt to 1, and calls sock_hold().  Here, struct\nubuf_info_msgzc indirectly holds a refcnt of the socket.  When the\nskb is sent, __skb_tstamp_tx() clones it and puts the clone into\nthe socket's error queue with the TX timestamp.\n\nWhen the original skb is received locally, skb_copy_ubufs() calls\nskb_unclone(), and pskb_expand_head() increments skb-\u003ecb-\u003eubuf.refcnt.\nThis additional count is decremented while freeing the skb, but struct\nubuf_info_msgzc still has a refcnt, so __msg_zerocopy_callback() is\nnot called.\n\nThe last refcnt is not released unless we retrieve the TX timestamped\nskb by recvmsg().  Since we clear the error queue in inet_sock_destruct()\nafter the socket's refcnt reaches 0, there is a circular dependency.\nIf we close() the socket holding such skbs, we never call sock_put()\nand leak the count, sk, and skb.\n\nTCP has the same problem, and commit e0c8bccd40fc (\"net: stream:\npurge sk_error_queue in sk_stream_kill_queues()\") tried to fix it\nby calling skb_queue_purge() during close().  However, there is a\nsmall chance that skb queued in a qdisc or device could be put\ninto the error queue after the skb_queue_purge() call.\n\nIn __skb_tstamp_tx(), the cloned skb should not have a reference\nto the ubuf to remove the circular dependency, but skb_clone() does\nnot call skb_copy_ubufs() for zerocopy skb.  So, we need to call\nskb_orphan_frags_rx() for the cloned skb to call skb_copy_ubufs().\n\n[0]:\nBUG: memory leak\nunreferenced object 0xffff88800c6d2d00 (size 1152):\n  comm \"syz-executor392\", pid 264, jiffies 4294785440 (age 13.044s)\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 cd af e8 81 00 00 00 00  ................\n    02 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00  ...@............\n  backtrace:\n    [\u003c0000000055636812\u003e] sk_prot_alloc+0x64/0x2a0 net/core/sock.c:2024\n    [\u003c0000000054d77b7a\u003e] sk_alloc+0x3b/0x800 net/core/sock.c:2083\n    [\u003c0000000066f3c7e0\u003e] inet_create net/ipv4/af_inet.c:319 [inline]\n    [\u003c0000000066f3c7e0\u003e] inet_create+0x31e/0xe40 net/ipv4/af_inet.c:245\n    [\u003c000000009b83af97\u003e] __sock_create+0x2ab/0x550 net/socket.c:1515\n    [\u003c00000000b9b11231\u003e] sock_create net/socket.c:1566 [inline]\n    [\u003c00000000b9b11231\u003e] __sys_socket_create net/socket.c:1603 [inline]\n    [\u003c00000000b9b11231\u003e] __sys_socket_create net/socket.c:1588 [inline]\n    [\u003c00000000b9b11231\u003e] __sys_socket+0x138/0x250 net/socket.c:1636\n    [\u003c000000004fb45142\u003e] __do_sys_socket net/socket.c:1649 [inline]\n    [\u003c000000004fb45142\u003e] __se_sys_socket net/socket.c:1647 [inline]\n    [\u003c000000004fb45142\u003e] __x64_sys_socket+0x73/0xb0 net/socket.c:1647\n    [\u003c0000000066999e0e\u003e] do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n    [\u003c0000000066999e0e\u003e] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80\n    [\u003c0000000017f238c1\u003e] entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nBUG: memory leak\nunreferenced object 0xffff888017633a00 (size 240):\n  comm \"syz-executor392\", pid 264, jiffies 4294785440 (age 13.044s)\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................\n    00 00 00 00 00 00 00 00 00 2d 6d 0c 80 88 ff ff  .........-m.....\n  backtrace:\n    [\u003c000000002b1c4368\u003e] __alloc_skb+0x229/0x320 net/core/skbuff.c:497\n    [\u003c00000000143579a6\u003e] alloc_skb include/linux/skbuff.h:1265 [inline]\n    [\u003c00000000143579a6\u003e] sock_omalloc+0xaa/0x190 net/core/sock.c:2596\n    [\u003c00000000be626478\u003e] msg_zerocopy_alloc net/core/skbuff.c:1294 [inline]\n    [\u003c00000000be626478\u003e]\n---truncated---","modified":"2026-03-20T12:33:10.975505Z","published":"2025-10-01T11:45:41.304Z","related":["SUSE-SU-2025:03615-1","SUSE-SU-2025:3761-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53489.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1f69c086b20e27763af28145981435423f088268"},{"type":"WEB","url":"https://git.kernel.org/stable/c/230a5ed7d813fb516de81d23f09d7506753e41e9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/281072fb2a7294cde7acbf5375b879f40a8001b7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/30290f210ba7426ff7592fe2eb4114b1b5bad219"},{"type":"WEB","url":"https://git.kernel.org/stable/c/426384dd4980040651536fef5feac4dcc4d7ee4e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/50749f2dd6854a41830996ad302aef2ffaf011d8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/602fa8af44fd55a58f9e94eb673e8adad2c6cc46"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb52e7f24c1d01a536a847dff0d1d95889cc3b5c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53489.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53489"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f214f915e7db99091f1312c48b30928c1e0c90b7"},{"fixed":"281072fb2a7294cde7acbf5375b879f40a8001b7"},{"fixed":"1f69c086b20e27763af28145981435423f088268"},{"fixed":"602fa8af44fd55a58f9e94eb673e8adad2c6cc46"},{"fixed":"230a5ed7d813fb516de81d23f09d7506753e41e9"},{"fixed":"43e4197dd5f6b474a8b16f8b6a42cd45cf4f9d1a"},{"fixed":"cb52e7f24c1d01a536a847dff0d1d95889cc3b5c"},{"fixed":"30290f210ba7426ff7592fe2eb4114b1b5bad219"},{"fixed":"426384dd4980040651536fef5feac4dcc4d7ee4e"},{"fixed":"50749f2dd6854a41830996ad302aef2ffaf011d8"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2023-53489.json"}}],"schema_version":"1.7.5"}