{"id":"DEBIAN-CVE-2023-52523","details":"In the Linux kernel, the following vulnerability has been resolved:  bpf, sockmap: Reject sk_msg egress redirects to non-TCP sockets  With a SOCKMAP/SOCKHASH map and an sk_msg program user can steer messages sent from one TCP socket (s1) to actually egress from another TCP socket (s2):  tcp_bpf_sendmsg(s1)\t\t// = sk_prot-\u003esendmsg   tcp_bpf_send_verdict(s1)\t// __SK_REDIRECT case     tcp_bpf_sendmsg_redir(s2)       tcp_bpf_push_locked(s2) \ttcp_bpf_push(s2) \t  tcp_rate_check_app_limited(s2) // expects tcp_sock \t  tcp_sendmsg_locked(s2)\t // ditto  There is a hard-coded assumption in the call-chain, that the egress socket (s2) is a TCP socket.  However in commit 122e6c79efe1 (\"sock_map: Update sock type checks for UDP\") we have enabled redirects to non-TCP sockets. This was done for the sake of BPF sk_skb programs. There was no indention to support sk_msg send-to-egress use case.  As a result, attempts to send-to-egress through a non-TCP socket lead to a crash due to invalid downcast from sock to tcp_sock:   BUG: kernel NULL pointer dereference, address: 000000000000002f  ...  Call Trace:   \u003cTASK\u003e   ? show_regs+0x60/0x70   ? __die+0x1f/0x70   ? page_fault_oops+0x80/0x160   ? do_user_addr_fault+0x2d7/0x800   ? rcu_is_watching+0x11/0x50   ? exc_page_fault+0x70/0x1c0   ? asm_exc_page_fault+0x27/0x30   ? tcp_tso_segs+0x14/0xa0   tcp_write_xmit+0x67/0xce0   __tcp_push_pending_frames+0x32/0xf0   tcp_push+0x107/0x140   tcp_sendmsg_locked+0x99f/0xbb0   tcp_bpf_push+0x19d/0x3a0   tcp_bpf_sendmsg_redir+0x55/0xd0   tcp_bpf_send_verdict+0x407/0x550   tcp_bpf_sendmsg+0x1a1/0x390   inet_sendmsg+0x6a/0x70   sock_sendmsg+0x9d/0xc0   ? sockfd_lookup_light+0x12/0x80   __sys_sendto+0x10e/0x160   ? syscall_enter_from_user_mode+0x20/0x60   ? __this_cpu_preempt_check+0x13/0x20   ? lockdep_hardirqs_on+0x82/0x110   __x64_sys_sendto+0x1f/0x30   do_syscall_64+0x38/0x90   entry_SYSCALL_64_after_hwframe+0x63/0xcd  Reject selecting a non-TCP sockets as redirect target from a BPF sk_msg program to prevent the crash. When attempted, user will receive an EACCES error from send/sendto/sendmsg() syscall.","modified":"2026-09-15T09:02:47.977273888Z","published":"2024-03-02T22:15:48.213Z","upstream":["CVE-2023-52523"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2023-52523"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.64-1"}]}],"versions":["6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52523.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.5.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52523.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.5.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52523.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}