---
id: "CVE-2026-98646"
kind: "vulnerability"
aliases: ["CVE-2026-98646"]
title: "Linux kernel: TCP listener teardown under BPF iterator triggers a sleep-in-atomic warning"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["bpf", "infrastructure", "linux-kernel", "tcp"]
not_affected_if: []
published_at: "2026-10-18T16:17:17+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:20:48+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98646", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: TCP listener teardown under BPF iterator triggers a sleep-in-atomic warning

When a BPF program destroys a listening TCP socket that still has queued children, the kernel calls cond_resched() while holding an RCU read lock, which trips a kernel debug check. The sources describe a kernel warning and a fix that skips the reschedule in BPF context; they do not describe code execution or data exposure.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98646

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

tcp: Skip cond_resched() in inet_csk_listen_stop() under BPF context

bpf_sock_destroy() runs from the tcp iterator, under rcu_read_lock(). If
the sock is a listener that still has children in its accept queue,
tcp_abort() ends up in inet_csk_listen_stop() and the cond_resched()
there trips the debug check:

BUG: sleeping function called from invalid context at net/ipv4/inet_connection_sock.c:1523
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 628, name: test_progs
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
locks held by test_progs/628: 3, last CPU#3:
 #0: ffff8881158cee18 (&p->lock){+.+.}-{4:4}, at: bpf_seq_read+0x56/0x1210
 #1: ffff8881106bb858 (sk_lock-AF_INET6){+.+.}-{0:0}, at: bpf_iter_tcp_seq_show+0x32b/0x4b0
 #2: ffffffffb435af20 (rcu_read_lock){....}-{1:3}, at: bpf_iter_run_prog+0x46b/0xde0
CPU: 3 UID: 0 PID: 628 Comm: test_progs Tainted: G        W           7.2.0+ #65 PREEMPT
Tainted: [W]=WARN
Call Trace:
 <TASK>
 dump_stack_lvl+0xc1/0xf0
 dump_stack+0x10/0x20
 __might_resched+0x3d2/0x610
 inet_csk_listen_stop+0x7b/0xbf0
 tcp_abort+0x23b/0x3b0
 bpf_sock_destroy+0xfc/0x140
 bpf_prog_448133d24601754f_iter_tcp6_server+0x81/0x8a
 bpf_iter_run_prog+0x538/0xde0
 bpf_iter_tcp_seq_show+0x26b/0x4b0
 bpf_seq_read+0x424/0x1210
 vfs_read+0x197/0xe40
 ksys_read+0x119/0x240
 __x64_sys_read+0x72/0xc0
 x64_sys_call+0x647/0x27e0
 do_syscall_64+0xe5/0x610
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fad39b28aca
RSP: 002b:00007ffc381c61c0 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ffc381c6a88 RCX: 00007fad39b28aca
RDX: 0000000000000032 RSI: 00007ffc381c6250 RDI: 0000000000000014
RBP: 00007ffc381c61e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 000055f077c1bbb0 R15: 00007fad3a0f3000
 </TASK>

The commit that added the kfunc already guards lock_sock() in tcp_abort()
and udp_abort() with has_current_bpf_ctx(), but missed the listener path.
Do the same for the cond_resched(). The loop runs inside the iterator's
rcu_read_lock(), it must not reschedule or report a quiescent state there.

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