{"id":"CVE-2025-21706","summary":"mptcp: pm: only set fullmesh for subflow endp","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: pm: only set fullmesh for subflow endp\n\nWith the in-kernel path-manager, it is possible to change the 'fullmesh'\nflag. The code in mptcp_pm_nl_fullmesh() expects to change it only on\n'subflow' endpoints, to recreate more or less subflows using the linked\naddress.\n\nUnfortunately, the set_flags() hook was a bit more permissive, and\nallowed 'implicit' endpoints to get the 'fullmesh' flag while it is not\nallowed before.\n\nThat's what syzbot found, triggering the following warning:\n\n  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 __mark_subflow_endp_available net/mptcp/pm_netlink.c:1496 [inline]\n  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_pm_nl_fullmesh net/mptcp/pm_netlink.c:1980 [inline]\n  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_nl_set_flags net/mptcp/pm_netlink.c:2003 [inline]\n  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_pm_nl_set_flags+0x974/0xdc0 net/mptcp/pm_netlink.c:2064\n  Modules linked in:\n  CPU: 0 UID: 0 PID: 6499 Comm: syz.1.413 Not tainted 6.13.0-rc5-syzkaller-00172-gd1bf27c4e176 #0\n  Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\n  RIP: 0010:__mark_subflow_endp_available net/mptcp/pm_netlink.c:1496 [inline]\n  RIP: 0010:mptcp_pm_nl_fullmesh net/mptcp/pm_netlink.c:1980 [inline]\n  RIP: 0010:mptcp_nl_set_flags net/mptcp/pm_netlink.c:2003 [inline]\n  RIP: 0010:mptcp_pm_nl_set_flags+0x974/0xdc0 net/mptcp/pm_netlink.c:2064\n  Code: 01 00 00 49 89 c5 e8 fb 45 e8 f5 e9 b8 fc ff ff e8 f1 45 e8 f5 4c 89 f7 be 03 00 00 00 e8 44 1d 0b f9 eb a0 e8 dd 45 e8 f5 90 \u003c0f\u003e 0b 90 e9 17 ff ff ff 89 d9 80 e1 07 38 c1 0f 8c c9 fc ff ff 48\n  RSP: 0018:ffffc9000d307240 EFLAGS: 00010293\n  RAX: ffffffff8bb72e03 RBX: 0000000000000000 RCX: ffff88807da88000\n  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000\n  RBP: ffffc9000d307430 R08: ffffffff8bb72cf0 R09: 1ffff1100b842a5e\n  R10: dffffc0000000000 R11: ffffed100b842a5f R12: ffff88801e2e5ac0\n  R13: ffff88805c214800 R14: ffff88805c2152e8 R15: 1ffff1100b842a5d\n  FS:  00005555619f6500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 0000000020002840 CR3: 00000000247e6000 CR4: 00000000003526f0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   \u003cTASK\u003e\n   genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]\n   genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]\n   genl_rcv_msg+0xb14/0xec0 net/netlink/genetlink.c:1210\n   netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2542\n   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219\n   netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]\n   netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347\n   netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891\n   sock_sendmsg_nosec net/socket.c:711 [inline]\n   __sock_sendmsg+0x221/0x270 net/socket.c:726\n   ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583\n   ___sys_sendmsg net/socket.c:2637 [inline]\n   __sys_sendmsg+0x269/0x350 net/socket.c:2669\n   do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  RIP: 0033:0x7f5fe8785d29\n  Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\n  RSP: 002b:00007fff571f5558 EFLAGS: 00000246 ORIG_RAX: 000000000000002e\n  RAX: ffffffffffffffda RBX: 00007f5fe8975fa0 RCX: 00007f5fe8785d29\n  RDX: 0000000000000000 RSI: 0000000020000480 RDI: 0000000000000007\n  RBP: 00007f5fe8801b08 R08: 0000000000000000 R09: 0000000000000000\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\n  R13: 00007f5fe8975fa0 R14: 00007f5fe8975fa0 R15: 000000\n---truncated---","modified":"2026-03-20T12:41:07.498954Z","published":"2025-02-27T02:07:20.458Z","related":["SUSE-SU-2025:01919-1","SUSE-SU-2025:01951-1","SUSE-SU-2025:01967-1","SUSE-SU-2025:1177-1","SUSE-SU-2025:1178-1","SUSE-SU-2025:1180-1","SUSE-SU-2025:20190-1","SUSE-SU-2025:20192-1","SUSE-SU-2025:20260-1","SUSE-SU-2025:20270-1","USN-7521-2"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21706.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1bb0d1348546ad059f55c93def34e67cb2a034a6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/22b0734c9401a74ed4ebd9e8ef0da33e493852eb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8ac344cbd84fda75e05e1f445f7f8fb24dc175e1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9e3d61620a3cd033319553b980ff3a350adbe1bc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/de3b8d41d2547452c4cafb146d003fa4689fbaf2"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21706.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21706"},{"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":"73c762c1f07dacba4fd1cefd15e24b419d42320d"},{"fixed":"22b0734c9401a74ed4ebd9e8ef0da33e493852eb"},{"fixed":"de3b8d41d2547452c4cafb146d003fa4689fbaf2"},{"fixed":"8ac344cbd84fda75e05e1f445f7f8fb24dc175e1"},{"fixed":"9e3d61620a3cd033319553b980ff3a350adbe1bc"},{"fixed":"1bb0d1348546ad059f55c93def34e67cb2a034a6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21706.json"}}],"schema_version":"1.7.5"}