{"id":"AZL-64734","summary":"CVE-2025-38181 affecting package kernel for versions less than 6.6.96.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ncalipso: Fix null-ptr-deref in calipso_req_{set,del}attr().\n\nsyzkaller reported a null-ptr-deref in sock_omalloc() while allocating\na CALIPSO option.  [0]\n\nThe NULL is of struct sock, which was fetched by sk_to_full_sk() in\ncalipso_req_setattr().\n\nSince commit a1a5344ddbe8 (\"tcp: avoid two atomic ops for syncookies\"),\nreqsk-\u003ersk_listener could be NULL when SYN Cookie is returned to its\nclient, as hinted by the leading SYN Cookie log.\n\nHere are 3 options to fix the bug:\n\n  1) Return 0 in calipso_req_setattr()\n  2) Return an error in calipso_req_setattr()\n  3) Alaways set rsk_listener\n\n1) is no go as it bypasses LSM, but 2) effectively disables SYN Cookie\nfor CALIPSO.  3) is also no go as there have been many efforts to reduce\natomic ops and make TCP robust against DDoS.  See also commit 3b24d854cb35\n(\"tcp/dccp: do not touch listener sk_refcnt under synflood\").\n\nAs of the blamed commit, SYN Cookie already did not need refcounting,\nand no one has stumbled on the bug for 9 years, so no CALIPSO user will\ncare about SYN Cookie.\n\nLet's return an error in calipso_req_setattr() and calipso_req_delattr()\nin the SYN Cookie case.\n\nThis can be reproduced by [1] on Fedora and now connect() of nc times out.\n\n[0]:\nTCP: request_sock_TCPv6: Possible SYN flooding on port [::]:20002. Sending cookies.\nOops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN NOPTI\nKASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]\nCPU: 3 UID: 0 PID: 12262 Comm: syz.1.2611 Not tainted 6.14.0 #2\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\nRIP: 0010:read_pnet include/net/net_namespace.h:406 [inline]\nRIP: 0010:sock_net include/net/sock.h:655 [inline]\nRIP: 0010:sock_kmalloc+0x35/0x170 net/core/sock.c:2806\nCode: 89 d5 41 54 55 89 f5 53 48 89 fb e8 25 e3 c6 fd e8 f0 91 e3 00 48 8d 7b 30 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 \u003c80\u003e 3c 02 00 0f 85 26 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b\nRSP: 0018:ffff88811af89038 EFLAGS: 00010216\nRAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff888105266400\nRDX: 0000000000000006 RSI: ffff88800c890000 RDI: 0000000000000030\nRBP: 0000000000000050 R08: 0000000000000000 R09: ffff88810526640e\nR10: ffffed1020a4cc81 R11: ffff88810526640f R12: 0000000000000000\nR13: 0000000000000820 R14: ffff888105266400 R15: 0000000000000050\nFS:  00007f0653a07640(0000) GS:ffff88811af80000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f863ba096f4 CR3: 00000000163c0005 CR4: 0000000000770ef0\nPKRU: 80000000\nCall Trace:\n \u003cIRQ\u003e\n ipv6_renew_options+0x279/0x950 net/ipv6/exthdrs.c:1288\n calipso_req_setattr+0x181/0x340 net/ipv6/calipso.c:1204\n calipso_req_setattr+0x56/0x80 net/netlabel/netlabel_calipso.c:597\n netlbl_req_setattr+0x18a/0x440 net/netlabel/netlabel_kapi.c:1249\n selinux_netlbl_inet_conn_request+0x1fb/0x320 security/selinux/netlabel.c:342\n selinux_inet_conn_request+0x1eb/0x2c0 security/selinux/hooks.c:5551\n security_inet_conn_request+0x50/0xa0 security/security.c:4945\n tcp_v6_route_req+0x22c/0x550 net/ipv6/tcp_ipv6.c:825\n tcp_conn_request+0xec8/0x2b70 net/ipv4/tcp_input.c:7275\n tcp_v6_conn_request+0x1e3/0x440 net/ipv6/tcp_ipv6.c:1328\n tcp_rcv_state_process+0xafa/0x52b0 net/ipv4/tcp_input.c:6781\n tcp_v6_do_rcv+0x8a6/0x1a40 net/ipv6/tcp_ipv6.c:1667\n tcp_v6_rcv+0x505e/0x5b50 net/ipv6/tcp_ipv6.c:1904\n ip6_protocol_deliver_rcu+0x17c/0x1da0 net/ipv6/ip6_input.c:436\n ip6_input_finish+0x103/0x180 net/ipv6/ip6_input.c:480\n NF_HOOK include/linux/netfilter.h:314 [inline]\n NF_HOOK include/linux/netfilter.h:308 [inline]\n ip6_input+0x13c/0x6b0 net/ipv6/ip6_input.c:491\n dst_input include/net/dst.h:469 [inline]\n ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]\n ip6_rcv_finish+0xb6/0x490 net/ipv6/ip6_input.c:69\n NF_HOOK include/linux/netfilter.h:314 [inline]\n NF_HOOK include/linux/netf\n---truncated---","modified":"2026-04-01T05:20:23.808280Z","published":"2025-07-04T14:15:24Z","upstream":["CVE-2025-38181"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38181"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.96.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-64734.json"}}],"schema_version":"1.7.5"}