ghsa-5wf2-hxf9-8hxr
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.
syzkaller reported [0] memory leaks of an UDP socket and ZEROCOPY skbs. We can reproduce the problem with these sequences:
sk = socket(AF_INET, SOCK_DGRAM, 0) sk.setsockopt(SOL_SOCKET, SO_TIMESTAMPING, SOF_TIMESTAMPING_TX_SOFTWARE) sk.setsockopt(SOL_SOCKET, SO_ZEROCOPY, 1) sk.sendto(b'', MSG_ZEROCOPY, ('127.0.0.1', 53)) sk.close()
sendmsg() calls msg_zerocopy_alloc(), which allocates a skb, sets skb->cb->ubuf.refcnt to 1, and calls sock_hold(). Here, struct ubuf_info_msgzc indirectly holds a refcnt of the socket. When the skb is sent, __skb_tstamp_tx() clones it and puts the clone into the socket's error queue with the TX timestamp.
When the original skb is received locally, skb_copy_ubufs() calls skb_unclone(), and pskb_expand_head() increments skb->cb->ubuf.refcnt. This additional count is decremented while freeing the skb, but struct ubuf_info_msgzc still has a refcnt, so __msg_zerocopy_callback() is not called.
The last refcnt is not released unless we retrieve the TX timestamped skb by recvmsg(). Since we clear the error queue in inet_sock_destruct() after the socket's refcnt reaches 0, there is a circular dependency. If we close() the socket holding such skbs, we never call sock_put() and leak the count, sk, and skb.
TCP has the same problem, and commit e0c8bccd40fc ("net: stream: purge sk_error_queue in sk_stream_kill_queues()") tried to fix it by calling skb_queue_purge() during close(). However, there is a small chance that skb queued in a qdisc or device could be put into the error queue after the skb_queue_purge() call.
In __skb_tstamp_tx(), the cloned skb should not have a reference to the ubuf to remove the circular dependency, but skb_clone() does not call skb_copy_ubufs() for zerocopy skb. So, we need to call skb_orphan_frags_rx() for the cloned skb to call skb_copy_ubufs().
[0]: BUG: memory leak unreferenced object 0xffff88800c6d2d00 (size 1152): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 cd af e8 81 00 00 00 00 ................ 02 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ backtrace: [<0000000055636812>] sk_prot_alloc+0x64/0x2a0 net/core/sock.c:2024 [<0000000054d77b7a>] sk_alloc+0x3b/0x800 net/core/sock.c:2083 [<0000000066f3c7e0>] inet_create net/ipv4/af_inet.c:319 [inline] [<0000000066f3c7e0>] inet_create+0x31e/0xe40 net/ipv4/af_inet.c:245 [<000000009b83af97>] __sock_create+0x2ab/0x550 net/socket.c:1515 [<00000000b9b11231>] sock_create net/socket.c:1566 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1603 [inline] [<00000000b9b11231>] __sys_socket_create net/socket.c:1588 [inline] [<00000000b9b11231>] __sys_socket+0x138/0x250 net/socket.c:1636 [<000000004fb45142>] __do_sys_socket net/socket.c:1649 [inline] [<000000004fb45142>] __se_sys_socket net/socket.c:1647 [inline] [<000000004fb45142>] __x64_sys_socket+0x73/0xb0 net/socket.c:1647 [<0000000066999e0e>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<0000000066999e0e>] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 [<0000000017f238c1>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
BUG: memory leak unreferenced object 0xffff888017633a00 (size 240): comm "syz-executor392", pid 264, jiffies 4294785440 (age 13.044s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 2d 6d 0c 80 88 ff ff .........-m..... backtrace: [<000000002b1c4368>] __alloc_skb+0x229/0x320 net/core/skbuff.c:497 [<00000000143579a6>] alloc_skb include/linux/skbuff.h:1265 [inline] [<00000000143579a6>] sock_omalloc+0xaa/0x190 net/core/sock.c:2596 [<00000000be626478>] msg_zerocopy_alloc net/core/skbuff.c:1294 [inline] [<00000000be626478>] ---truncated---
{
"affected": [],
"aliases": [
"CVE-2023-53489"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-01T12:15:51Z",
"severity": null
},
"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\u0027\u0027, MSG_ZEROCOPY, (\u0027127.0.0.1\u0027, 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\u0027s 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\u0027s 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---",
"id": "GHSA-5wf2-hxf9-8hxr",
"modified": "2025-10-01T12:30:30Z",
"published": "2025-10-01T12:30:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-53489"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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- Confirmed: The vulnerability is confirmed from an analyst perspective.
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- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.