{ "schema_version": "1.6.1", "id": "RPI-CVE-2023-52523", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2023-52523" ], "published": "2024-03-02T21:53:07Z", "summary": "bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets\n\nWith a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages\nsent from one TCP socket (s1) to actually egress from another TCP\nsocket (s2):\n\ntcp_bpf_sendmsg(s1)\t\t// = sk_prot->sendmsg\n tcp_bpf_send_verdict(s1)\t// __SK_REDIRECT case\n tcp_bpf_sendmsg_redir(s2)\n tcp_bpf_push_locked(s2)\n\ttcp_bpf_push(s2)\n\t tcp_rate_check_app_limited(s2) // expects tcp_sock\n\t tcp_sendmsg_locked(s2)\t // ditto\n\nThere is a hard-coded assumption in the call-chain, that the egress\nsocket (s2) is a TCP socket.\n\nHowever in commit 122e6c79efe1 (\"sock_map: Update sock type checks for\nUDP\") we have enabled redirects to non-TCP sockets. This was done for the\nsake of BPF sk_skb programs. There was no indention to support sk_msg\nsend-to-egress use case.\n\nAs a result, attempts to send-to-egress through a non-TCP socket lead to a\ncrash due to invalid downcast from sock to tcp_sock:\n\n BUG: kernel NULL pointer dereference, address: 000000000000002f\n ...\n Call Trace:\n \n ? show_regs+0x60/0x70\n ? __die+0x1f/0x70\n ? page_fault_oops+0x80/0x160\n ? do_user_addr_fault+0x2d7/0x800\n ? rcu_is_watching+0x11/0x50\n ? exc_page_fault+0x70/0x1c0\n ? asm_exc_page_fault+0x27/0x30\n ? tcp_tso_segs+0x14/0xa0\n tcp_write_xmit+0x67/0xce0\n __tcp_push_pending_frames+0x32/0xf0\n tcp_push+0x107/0x140\n tcp_sendmsg_locked+0x99f/0xbb0\n tcp_bpf_push+0x19d/0x3a0\n tcp_bpf_sendmsg_redir+0x55/0xd0\n tcp_bpf_send_verdict+0x407/0x550\n tcp_bpf_sendmsg+0x1a1/0x390\n inet_sendmsg+0x6a/0x70\n sock_sendmsg+0x9d/0xc0\n ? sockfd_lookup_light+0x12/0x80\n __sys_sendto+0x10e/0x160\n ? syscall_enter_from_user_mode+0x20/0x60\n ? __this_cpu_preempt_check+0x13/0x20\n ? lockdep_hardirqs_on+0x82/0x110\n __x64_sys_sendto+0x1f/0x30\n do_syscall_64+0x38/0x90\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nReject selecting a non-TCP sockets as redirect target from a BPF sk_msg\nprogram to prevent the crash. When attempted, user will receive an EACCES\nerror from send/sendto/sendmsg() syscall.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v6", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7l", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v8", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-2712", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v6", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v7l", "binary_version": "1:6.1.54-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi4-rpi-v8", "binary_version": "1:6.1.54-1+rpt2" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.57" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.57" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.57", "compiled_filter": false }, "1:6.1.54-1+rpt2": { "linux_commit": "2906f7abdc03d4a92b6b0e2e0c87ea2a9dffe8f7", "upstream_version": "6.1.54", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.57" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2023-52523" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/bc8b89b6963803a123f64aa9494155a037b3d728" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b8f97e47b6fb84fcf2f5a22e725eefb6cf5070c2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/ded6e448028f0f91b6af35985afca01fa02a9089" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b80e31baa43614e086a9d29dc1151932b1bd7fc5" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:24:39Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - Exploitation requires local bpf() setup of a SOCKMAP/SOCKHASH with an sk_msg verdict program plus send/sendto/sendmsg on a sockmap-enrolled TCP socket; the crash path is the local tcp_bpf_sendmsg \u2192 tcp_bpf_sendmsg_redir chain, not remote packet processing.\nAC:L - The attacker fully controls map population (TCP source and non-TCP redirect target), the sk_msg redirect verdict, and the triggering sendmsg; the type confusion is deterministic and needs no race or uncontrolled layout.\nPR:L - SOCKMAP/sk_msg creation needs CAP_NET_ADMIN/CAP_BPF, but those are commonly held by networking containers and can be delegated via BPF tokens; once a sockmap sk_msg redirect path exists, the send trigger is an ordinary local operation, matching other sockmap scores.\nUI:N - The attacker performs map setup, program attach, and the triggering sendmsg themselves; no victim action is required.\nS:U - The type confusion and resulting heap OOB/crash remain inside the host kernel\u2019s security authority; this is standard local kernel impact, not a VM/IOMMU/sandbox boundary crossing.\nC:H - tcp_bpf_push runs tcp_rate_check_app_limited() on the non-TCP target, reading tcp_sock fields (e.g. write_seq/mss_cache/delivered at offsets \u22651480) past udp_sock (1344) or unix_sock (1152), i.e. heap OOB reads of adjacent groomable objects.\nI:H - The same path writes tp->app_limited at offset 1780 past the smaller socket object (heap OOB write), and treating a non-TCP sock as tcp_sock is type confusion, which is High integrity impact under scoring guidance.\nA:H - The demonstrated result is a kernel NULL pointer dereference in tcp_tso_segs (icsk_ca_ops) reached via tcp_sendmsg_locked, causing an oops/panic that the attacker can repeat at will." } } }