{"cve":"CVE-2022-49372","nvd":{"published":"2025-02-26T07:01:13.870","modified":"2026-06-17T05:17:51.530","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: tcp_rtx_synack() can be called from process context\n\nLaurent reported the enclosed report [1]\n\nThis bug triggers with following coditions:\n\n0) Kernel built with CONFIG_DEBUG_PREEMPT=y\n\n1) A new passive FastOpen TCP socket is created.\n   This FO socket waits for an ACK coming from client to be a complete\n   ESTABLISHED one.\n2) A socket operation on this socket goes through lock_sock()\n   release_sock() dance.\n3) While the socket is owned by the user in step 2),\n   a retransmit of the SYN is received and stored in socket backlog.\n4) At release_sock() time, the socket backlog is processed while\n   in process context.\n5) A SYNACK packet is cooked in response of the SYN retransmit.\n6) -> tcp_rtx_synack() is called in process context.\n\nBefore blamed commit, tcp_rtx_synack() was always called from BH handler,\nfrom a timer handler.\n\nFix this by using TCP_INC_STATS() & NET_INC_STATS()\nwhich do not assume caller is in non preemptible context.\n\n[1]\nBUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180\ncaller is tcp_rtx_synack.part.0+0x36/0xc0\nCPU: 10 PID: 2180 Comm: epollpep Tainted: G           OE     5.16.0-0.bpo.4-amd64 #1  Debian 5.16.12-1~bpo11+1\nHardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021\nCall Trace:\n <TASK>\n dump_stack_lvl+0x48/0x5e\n check_preemption_disabled+0xde/0xe0\n tcp_rtx_synack.part.0+0x36/0xc0\n tcp_rtx_synack+0x8d/0xa0\n ? kmem_cache_alloc+0x2e0/0x3e0\n ? apparmor_file_alloc_security+0x3b/0x1f0\n inet_rtx_syn_ack+0x16/0x30\n tcp_check_req+0x367/0x610\n tcp_rcv_state_process+0x91/0xf60\n ? get_nohz_timer_target+0x18/0x1a0\n ? lock_timer_base+0x61/0x80\n ? preempt_count_add+0x68/0xa0\n tcp_v4_do_rcv+0xbd/0x270\n __release_sock+0x6d/0xb0\n release_sock+0x2b/0x90\n sock_setsockopt+0x138/0x1140\n ? __sys_getsockname+0x7e/0xc0\n ? aa_sk_perm+0x3e/0x1a0\n __sys_setsockopt+0x198/0x1e0\n __x64_sys_setsockopt+0x21/0x30\n do_syscall_64+0x38/0xc0\n entry_SYSCALL_64_after_hwframe+0x44/0xae","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/0a0f7f84148445c9f02f226928803a870139d820","https://git.kernel.org/stable/c/0a375c822497ed6ad6b5da0792a12a6f1af10c0b","https://git.kernel.org/stable/c/3db889f883e65bbd3b1401279bfc1e9ed255c481","https://git.kernel.org/stable/c/58bd38cbc961fd799842b7be8c5222310f04b908","https://git.kernel.org/stable/c/88cd232146207ff1d41dededed5e77c0d4438113"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2022-49372","score":0.00291,"percentile":0.21668,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}