ghsa-fpqf-4vc3-w3r3
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
mptcp: Fix proto fallback detection with BPF
The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() syn_recv_sock()/subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <== sockops bpf_sock_map_update(sk) <== call bpf helper tcp_bpf_update_proto() <== update sk_prot '''
When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_syn_recv_sock() subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() '''
Then, this subflow can be normally used by sockmap, which replaces the native sk_prot with sockmap's custom sk_prot. The issue occurs when the user executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops(). Here, it uses sk->sk_prot to compare with the native sk_prot, but this is incorrect when sockmap is used, as we may incorrectly set sk->sk_socket->ops.
This fix uses the more generic sk_family for the comparison instead.
Additionally, this also prevents a WARNING from occurring:
result from ./scripts/decode_stacktrace.sh: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \ (net/mptcp/protocol.c:4005) Modules linked in: ...
PKRU: 55555554 Call Trace: do_accept (net/socket.c:1989) __sys_accept4 (net/socket.c:2028 net/socket.c:2057) __x64_sys_accept (net/socket.c:2067) x64_sys_call (arch/x86/entry/syscall_64.c:41) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f87ac92b83d
---[ end trace 0000000000000000 ]---
{
"affected": [],
"aliases": [
"CVE-2025-68227"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-16T14:15:56Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: Fix proto fallback detection with BPF\n\nThe sockmap feature allows bpf syscall from userspace, or based\non bpf sockops, replacing the sk_prot of sockets during protocol stack\nprocessing with sockmap\u0027s custom read/write interfaces.\n\u0027\u0027\u0027\ntcp_rcv_state_process()\n syn_recv_sock()/subflow_syn_recv_sock()\n tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB)\n bpf_skops_established \u003c== sockops\n bpf_sock_map_update(sk) \u003c== call bpf helper\n tcp_bpf_update_proto() \u003c== update sk_prot\n\u0027\u0027\u0027\n\nWhen the server has MPTCP enabled but the client sends a TCP SYN\nwithout MPTCP, subflow_syn_recv_sock() performs a fallback on the\nsubflow, replacing the subflow sk\u0027s sk_prot with the native sk_prot.\n\u0027\u0027\u0027\nsubflow_syn_recv_sock()\n subflow_ulp_fallback()\n subflow_drop_ctx()\n mptcp_subflow_ops_undo_override()\n\u0027\u0027\u0027\n\nThen, this subflow can be normally used by sockmap, which replaces the\nnative sk_prot with sockmap\u0027s custom sk_prot. The issue occurs when the\nuser executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops().\nHere, it uses sk-\u003esk_prot to compare with the native sk_prot, but this\nis incorrect when sockmap is used, as we may incorrectly set\nsk-\u003esk_socket-\u003eops.\n\nThis fix uses the more generic sk_family for the comparison instead.\n\nAdditionally, this also prevents a WARNING from occurring:\n\nresult from ./scripts/decode_stacktrace.sh:\n------------[ cut here ]------------\nWARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \\\n(net/mptcp/protocol.c:4005)\nModules linked in:\n...\n\nPKRU: 55555554\nCall Trace:\n\u003cTASK\u003e\ndo_accept (net/socket.c:1989)\n__sys_accept4 (net/socket.c:2028 net/socket.c:2057)\n__x64_sys_accept (net/socket.c:2067)\nx64_sys_call (arch/x86/entry/syscall_64.c:41)\ndo_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)\nentry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\nRIP: 0033:0x7f87ac92b83d\n\n---[ end trace 0000000000000000 ]---",
"id": "GHSA-fpqf-4vc3-w3r3",
"modified": "2025-12-16T15:30:46Z",
"published": "2025-12-16T15:30:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68227"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/037cc50589643342d69185b663ecf9d26cce91e8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1a0d5c74af9b6ba9ffdf1172de5a1a6df5922a00"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/344974ea1a3ca30e4920687b0091bda4438cebdb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7ee8f015eb47907745e2070184a8ab1e442ac3c4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/92c4092fe012ecdfa5fb05d394f1c1d8f91ad81c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9b1980b6f23fa30bf12add19f37c7458625099eb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c77b3b79a92e3345aa1ee296180d1af4e7031f8f"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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